There are two possible scenarios:
- Your contract is with Bob, not with Peter. In this case it doesn't matter if Bob did not pay his part to Peter. Your contract with Bob does nit involve him. Peter will have to ask the money from Bob. But that also means that, as long as you had access to the house, you are not entitled for a refund for the 450 €. The deposit is a different story. As long as there are no reasons to hold back the deposit (e.g. for repairs you have caused), he will have to pay it back (with 3 months of interest).
- Bob was acting Peter's proxy. Your contract then is with Peter. Then it will matter if Bob has accepted the money in Peter's name and was entitled to do so. That means you have paid to Peter and have to ask him for a refund. Otherwise, you can ask the money back from Bob. In any case you can ask the deposit from Peter.