I had something happen like that, only with Paypal and my bank.
My parents bought tupperware for $30 and charged it to Paypal. Our Paypal account was set up with my dad's credit, but also tied to my bank account. For whatever reason, Paypal tried to use money from my bank account first (instead of going to the credit card). Of course, I didn't have the money and was charged a $35 NSF fee from my bank. Couple days later, we're wondering why the payment hasn't gone through and I check my balance again and behold,
another $35 NSF fee. In Paypal's infinite wisdom, it then decided to charge my dad's credit card.
In the end, my parents' $30 tupperware ended up costing three times that amount.