Stunna, doesnt that every account in PD got its own unique deposit address ? and of course only those who could login into the account will know what the address is, so if someone know what the deposit address of that account it, I think that is a solid proof that he own that account
Even though PD has its own deposit address for each account, most of the people who deposit, have their addresses used on bitcointalk. Due to the transparency of bitcoin, someone could be following the transactions on your address, and figure out the deposit address, and can just email the support as an imposter.