Regardless of whether or not the department that gave you permission to trade BitCoins was authorized to, you have their permission. In commerce law, this is referred to as "principal and agent". The agent (say a teller at a bank) is understood to represent the principal (the bank manager) and vice-versa. If they misrepresent, it's the bank that must keep its word to you - not you that must be inconvenienced by the bank. Same goes here.
This is only applicable and useful if you have evidence to support such permission. Satori is absolutely right that the agent(s) represent the entity and thus if they misrepresent the entity the entity is liable for such misrepresentation. Without evidence of the misrepresentation it would be foolish to enter a court and attempt to hold the entity responsible. Always collect evidence when interacting with PayPal and similar companies. It is perfectly legal to record a telephone conversation with PayPal and many other companies without notifying them you are recording (in ALL US states) and such recording can be used as evidence in court.In 1992 a real court ruled that PayPal couldn't include that proviso, because it fraudulently convinced Paypal users that they had no access to real courts as a result. Last I checked a few months ago, the proviso was still in PayPal's EULA despite the court ruling.
Are you sure that was 1992? 