Z-STACK Avis 

Excellent customer service! Grateful for the help and problem solving!

The zsleeep really makes a difference in my sleep!!! They are very responsive and helful

i like ordering these supplements they help me

The customer service is very responsive. I have used the Zelenko products for years now and they really helped me with my health issues.

I love my Z-Stack!! This month my package arrived opened and empty! I reached out and within a short while a replacement order was on the way! Thank you for your unmatched customer service!

I have been taking Z-Stack for years. I know without s doubt it has helped me fight off colds and other ailments. Several years ago, I got COVID, even after taking 3 sticks(never again) but with all the ingredients in Z-Stack, it was like having a mild cold and it was gone in days. I WILL ALWAYS use Z-Stack as I do believe in the founding father and now the company.
Jeff

We started taking Z-stack a short time after COVID started. We continue to take them daily and feel this has helped us immensely over the years by avoiding colds, flu and even being exposed to covid. We are thankful to Dr Z for his discovery as we feel much safer taking our Z-STACK. A great product and customer service is outstanding.

I have been taking Z-Stack since COVID. I am 70+ years old and I have not had any illness. I even went to Mexico the end of Oct/Nov 2020 with no issues. I highly recommend this product. I have made other International trips in the last few years and faithfully take Z-Stack.

When I contacted Shannon from Zelenko labs about my missing shipment, she immediately replaced it with another one. I greatly appreciate the value they see in their customers and vice versa.

I have taken Z Stack since 2021 and have not had a sick day in the time since. Never got Covid. Very good immune protection. (I added K2 to the regimen some time thereafter due to learning that this is needed with the D3 to redirect calcium from the arteries.)
Dr Zelenco has passed, but his legacy continues on with this great formula Z Stack.

I have been on this product since 2022 and have not had a sick day since

For three years Z-Stack ihas been an exceptional preventive against bacteria and virus both - takes me literally 15 minute to break an attack. It also seems to prevent Covid 19. No side effects at all except good health. Most grateful to Dr. Z.

On-line customer service was excellent. Responded to me in less than 2 hours. Issue was resolved quickly an efficiently. BEST customer service I have ever recieved.

Kindness expressed
Willingness to pause delivery schedule

Great customer service! Quick to respond and very helpful. I absolutely LOVE the Zstack. I don’t want to ever be without it.

I had an order "swap products" question this weekend and sent off an email asking how to do it! Well, I figured it out myself, made the swap, it was a quite easy actually. There was an email from the Z-stack customer service department in my inbox this morning, that was quick! We went over the details of my account and order, all was well. Been with Dr Zelenko for several years now, great products, great company!

Choosing some of my supplements from Z stack may have been one of the best choices I made in years for my health. The vitamins I choose to use are the z stack with vitamin c, d, zinc and quercetin. Prior to these vitamins, I would take just vitamin c and d. I have learned so much from Dr Zelenko during the COVID times, I really didn’t trust many drs at the time but he was true to his word, may he Rest in Peace. This company is legit if you want your immune system working well, in my opinion, the company works with you and the delivery is pretty fast. I really do appreciate this company still existing and I pray they continue.

I have been taking this for many years in fact since it came out. I have not gotten sick and I truly believe it is because I take this every day. I have it on auto ship so I am never with out it.

This company is always there to help whether it’s adding a bottle or skip a month. Thank you for your outstanding service

Customer service is everything !!! I credit Zelenko for providing courteous, timely, professional customer service from start to finish. The product is #1 in my experience during COVID epidemic. I continue using the product faithfully. Opting -out from taking the vaccination was 100% due to my faith in GOD and the product living up to its' claims to strengthen my immune system ! To date, I have not been disappointed and commend Dr. Zelenko for developing his outstanding formula. GOD bless him!