not to put a damper on this
but it could be the banks fault and got the accounts mixed up due to silimarities in the account numbers it has happened to me before and they fixed everything.
something went down at the information center that send and recieves your information and gets your account right with what you spend
the other person bought something and i got charged with what they spend and them with mine.
luckily for me whoever they were only bought 30 dollars worth of stuff with mine and i bought 399 worth of stuff with theirs
but the bank fixed it the next day