Sorry to hear of your experience. It looks as if you took some good from the experience. Always make time to inspect and test the gear.

Always ask the shop what the policy is regarding rental gear and refunds prior to leaving with the gear.

I try to rent paying via credit card, it the owners refuses to refund when they clearly should, I call the credit card company and refuse payment.

As far as PADI every agency has bad seeds you unfortunately found one.
Even though you only dive a few times every year, check ahead if possible with you local dive shop and find out who they use or better who they don't. I would look into a least you own mask, they don't take that much room up and it's a lot better then ever putting sometime moldy on.
Scuba Mama