I wouldn't contact anyone if its not necessary. We didn't and used it to buy add-ons. Before that, I called and they tried telling me some story of how it wasnt ours but we pay the bill. We knew exactly when and where that amount came from. Moral of the story...they will never give you money if they know there's a slight chance u could be talked out of it.
Was actually contacted by Boost Agent regarding my post. They were very helpful and helped me with my dilemma. It turns out all I had to do was stop the auto pay for the account so that I could access the amount already paid. So simple I never thought about that.