I actually have a couple of complaints against Paypal.
Paypal has a horrible habit of withdrawing funds from attached bank accounts without checking to see if the sufficient funds are even available, even when you tell them not to use the bank account as a funding source. They have overdrawn my bank account on three separate occasions, including most recently when they "linked" my paypal account to my ebay account as an automatic transaction, which I didn't authorize, each time they siphoned funds out of my bank account without my authorization, even when I provided an alternate funding source without the bank account as the source.
In addition, they "take" the funds from your bank account, however, do not report that they took the funds to your financial institution until several hours later, which makes it difficult to figure out ledger balances (When you are unsure of which account was charged) and if they actually charge the proper account. Which is so unlike any other business, which posts transactions within seconds of charging any type of account.
I was forced to contact the sellers several times that paypal had made unauthorized transactions to the wrong accounts, which the sellers had refunded, however, the funds never returned directly back to the bank account, and they would force me to will out an ACH transaction after placing a 5-day hold on my refunded funds.