Bad unfriendly calling site

I owe Vodocom a payment. However when I call to get the amount I am asked for ID number. I enter my ID number and am told it is invalid so I am unable to find out what my payment is. I have called back repeatedly and they have said my ID is invalid, which is ridiculous. I am sick of Vodacom and have problems with them before. As soon as I have the opportunity, I am going to leave them.