Z-STACKReviews of zstacklife.com

I have been a faithful Zelenko Labs customer and subscription customer for approximately two years. I believe in the products, and I have intentionally continued supporting this company because of my respect for Dr. Vladimir Zelenko, his story, his legacy, and what the company represents. Unfortunately, my recent experience with customer service—specifically with a supervisor—was extremely disappointing. I called because I had a simple question about my subscription pricing. The amount appeared higher than I expected, and I wanted to understand and confirm the rate. Instead of being able to have a straightforward customer-service conversation, I found the supervisor unusually defensive and sensitive to my questions. What concerns me most is what happened afterward. My subscription order was scheduled to process on September 18. The payment method shown on my account had not expired or changed. Yet following my conversation with the supervisor, my order did not process. My account first displayed a payment-method error and then stated that there was trouble with my account and directed me to contact support. Given the timing and what occurred during the call, I was left with the strong impression that something was done to my account that interfered with the processing of my scheduled shipment. If that is not what happened, I would welcome Zelenko Labs reviewing the account history and explaining exactly what caused it. This is particularly troubling because I was not calling to cancel, complain about the products, or create a problem. I am a long-standing customer simply asking a question about what I was being charged. A customer should be able to question a price or ask for clarification without feeling that the relationship—or an upcoming order—could somehow be affected. I continue to have great respect for Dr. Zelenko’s legacy and have been very pleased with the products themselves. My concern is with the customer-service culture I experienced. Questions from loyal customers should be welcomed, not taken personally. And supervisors, especially, should model professionalism, emotional maturity, transparency, and respect. I hope leadership takes this seriously, reviews what occurred with my account, and ensures that customers can ask reasonable questions without experiencing this kind of response.

Their shipping is super slow. It takes a month to arrive. I'm not happy at all.

Zstacklife has been full of contradictions, gaslighting and evasive customer service. They sent my shipment confirmation at 1:16 PM, only a few hours before closing. I didn’t see it until after they were closed, and when I called the next morning, they said it had already shipped and refused to cancel. When I brought up the late confirmation, the rep denied the timing despite the clear timestamp. When I emailed support with the screenshot, they dodged the issue entirely and blamed a credit card problem that wasn’t even relevant. My online account also marked the order as “Ready for pickup,” which is odd for an online-only business. The most concerning part? Instead of addressing my questions or correcting the issue, the company cancelled my subscriptions. A transaction like this is akin to a toddler throwing a tantrum, but a health company to shut down the conversation rather than resolve it is inexcusable. This is extremely toxic, dismissive, and unprofessional.

Couldn’t tell if this product helped or not with immunity issues. What I can say is that if you get a subscription, it’s not that easy to stop it. It is common these days I guess to get no customer service and finding a place to submit a request or complaint is a lot of fun. I have combined bottles to make room in my cabinet but still have seven bottles… when you think you have cancelled … guess again.

Not sure what is going on with this company, but it is not good. After I placed an order for 2 bottles of Z-Flu on 04/30/25, they sent an e-mail on 05/08/25 saying..."We’re reaching out with an important update about your recent order for Z-Flu.Due to an unexpected backorder, we’re currently unable to ship your Z-Flu bottle as scheduled. We sincerely apologize for the inconvenience and are working hard to resolve the issue as quickly as possible". I have sent NUMEROUS e-mails telling them to refund my money to my credit card. Today is 05/15/25 and they have still not refunded my money! This is not the first time this company has not fulfilled my order, but I thought I'd give them one last try. NEVER AGAIN! BUYER BEWARE!

Does anyone else's Zstack smell/taste like stink bugs? I've been getting this product for years and it never smelled like this! I've actually gotten sick/upset stomach, so have to stop taking it. I too, have had issues with getting my purchases timely and noticed that you cannot remove/delete credit cards that you put on file. I've referred family & friends to this product but no more!

I’ve been using Z-stack and Z-Flu for 3-4 years now and liked it. From my experience their customer service has become horrendous! In the past you could speak with a real person. Not anymore. It’s all automated via email only. I’m still waiting on an order from their Black Friday sale November 28th! Another two orders from December and January also. They keep saying “shipping tracking numbers going out this week.” But it never happens. Right now I’m out nearly $160 and I have a bad feeling they are blowing me off. If I ever get my order, I will not purchase anymore. I use to recommend their products, but now I’m embarrassed that I did. Use caution when ordering.

Absolutely horrible service I have been charged twice and not received my kid's vitamins. They charged me once for an order I didn't place. I received a terrible quality product in the summer months that looked like it had melted during shipping. Definitely do NOT do business with this company.