How exactly was the account hacked?
I have no idea, the only possibility- "crack" password.
edit: didn't see that theymos said to open a thread in meta about this situation
This is instruction to me via PM, because I have contact with him.
the borrower could potentially claim that he made a series of payments to your address
borrower(I have contact with him also) never has claim this, and he does not have control over account.
Currently account controls, a person who has nothing to do neither with me nor with borrower. he also demanded ransom from me.