Soo an update:
I made an account with limited access to the BO and an FTP account to the module's folder. The developer is totally incompetent. They have been lying for days. First they said they were going to tell me what changes they make but that was a total lie. The module, which breaks our website, has been enabled and then just left, leaving our website broken. The developer insisted he hasn't even been on our BO. Then how did the module enable itself? His next response came just a few minutes later and he said "the job has been completed" and the module was not touched since I last disabled it. LOL! What a scam. This is the module in question by the way. https://addons.prestashop.com/en/website-performance/44977-super-speed-incredibly-fast-gtmetrix-optimization.html#reviews
Not to mention, the way the show off these GTMetrix results to promote their module is a total lie. Every website with 0 products will turn up with grade A.
I was given prestashop's support email ([email protected]) which is not responding to my emails either..
Edit: Can't even review their module. What a surprise!