Low Google PageSpeed score despite WP Fastest Cache Premium

Today I bought WP Fastest Cache Premium. I did all the optimizations available, but when I check my website via Google Page Speed I get a score of only 36.

I am very dissatisfied with your product and I am thinking about asking for a refund. Could you please tell me an email address where I can send details of my website to so that someone from your team can have a look at the issue? Thank you very much. I do NOT want to make the website URL public.