Vodacom incompetence

Vodacom keeps phoning me to "pay" my account that is in "arrears". I know I pay the exact amount in store or a little extra each month. When asking them how much is in arrears they informed me of the amount, when I asked what this is for I was informed that I have another sim card on my name. I DID NOT authorize another contact to be opened on my name. I only upgraded my existing account when it was due. I have been in store multiple times, given in an affidavit so this contract can be removed off of my name. It's been a month and still NOTHING has been done, I am still receiving phone calls asking me to pay this unauthorized contract. I don't even know where this sim card is or who is using it.

Vodacom is quick to ask for money but not too keen on sorting faults out that have occurred due to them.

Thank you for giving me a bad credit record, AGAIN as I have even stopped my debit orders with them because they cannot manage that either, I'd rather drive to a store to help them get their jobs done.