You can trust them.
Although unfortunately my school denied the waiver, I have only good things to say about PSI. They are extremely organized—from their website to the customer service. Everything is in its right place. The waiver instructions are easy to find, every document you need is available and well labeled. You’ll have no trouble with anything whatsoever with them. In my case, within less than two days, they have already confirmed my refund + cancellation with no trouble. I’m sure my school was a specific case, and if you want to try waiving your school insurance i’d definetly recommend PSI.