Vodacom upgrades without my permision!

How can contracts be upgraded without my permission?

3 of the sim cards on my contract were upgraded without my knowledge- I have called in twice to cancel these, and have been promised that investigations will be done, however nothing has been done. In the meantime I am being billed every month.

Today when I called in a call centre consultant (Lincoln) told me "I hadn't asked him nicely" to cancel the contracts! Perhaps Vodacom needs to teach their staff who the customers are?