I tried the Cortexi for over 60 days. The customer service group came from some outfit named zendesk. They hijack all the emails addressed to cortexi. They were quite nice in the beginning, even granting me an additional 30 days to try the Cortexi. Well, after 65 days it was clear that it had done nothing for my tinnitus. I called to return it per the guarantee. First they offered to settle things with a 50% discount. I declined that. Then they went to 60%, I declined that. That is when I was told that to get the full refund, I had to return all the bottles that I had ordered, EVEN THE EMPTY ONES. Cortexi's guarantee does not specify this. It does say that you can even return empty bottles but does not say that they must be included for the full refund. When I called that to the attention of zendesk, they appreciated me calling that to their attention but remained obstinate that I would only be refunded based on the number of bottles returned. Fortunately I had just emptied one of the bottles and was able to retrieve it from the garbage. Now I ask you, who in their right mind keeps an empty bottle around for 30 days when they didn't even know that they had to return it??

Bottom line is that I will only be refunded for 5 bottles. In other words the guarantee only works for unused bottles unless one is OCD enough to keep empty bottles around!

Based on other reviews, I sent my material back with a USPS tracking number so that they will not be able to say that they did not receive it.

So, two things--
1. the Cortexi did not work for me at all even though I used faithfully in compliance with their directions.
2. Their return policy is disingenuous and a scam of sorts.
3. Their customer service arm-- zendesk appears to be unable to apply common sense to their policies!