I recently bought a game from Steam on an account which I have multiple games. The next thing I know, Paypal stopped the payment, thinking that it might be linked to fraud. They then required a response from Steam.
Steam then simply shut my account down, and told me that I had to resolve it with Paypal. Paypal have told me that Steam have to resolve the issue.
I've since sent 3 three emails asking Steam to give me the details to make a new payment via paypal, but after several days they have still not responded.
Steam has terrible customer support, with even worse response times. When they do reply, it's normally a canned response which bears little relevance to your question.
My advice is: stay away from Steam as much as you can, if something does go wrong, you lose everything and they don't care.