Incorrect statement with account in arrears

Vodacom has been sending me statements belonging to another person for a year now. Now they say that my account is in arrears, which I know is not the case. When I mailed them regarding this incorrect statement, they rep**** that I had to send some personal information so that they can authenticate me, which I did. Then they came back and said that the information was not sufficient to authenticate me and they threatened to suspend my account until this arrears, that is not mine, has been paid. I am utterly disgusted. How do they manage to send an incorrect statement to a customer for a year? Vodacom, if you suspend my account, all hell is going to break lose. I want a detailed reconciliation of my account from the day that my account allegedly went into arrears and I want it today.