I have high feedback on Playerauctions, I mainly sell OSRS accounts there everything from maxed pures to Main, sold mains over 120 combat with high total levels.
Never actually had a problem with them. First you give the account details, the buyer logs in, then within 3 days, they have to confirm the account details are accurate. Sometimes customers confirms the account instantly within few hours, some people forget about it. So after that 3 days, the order automatically gets confirmed, then you have to wait x amount of days to receive your disbursement (money).
Some buyers usually buy 1 year insurance converage when buying an account. In case of any recoveries etc.
Oh forget to say that. I did receive a complaint from a customer that the account got recovered as soon as he purchased it, but my feedback helped me in the case, so the buyer got their refund declined. In case of any issues, just be calm and provide as many proof as possible, be nice and PA will be on your side if you have been with them for some time.