Debit order in contravention of contract

I'm unhappy about the service I'm receiving from Vodacom as well as Homemark regarding my contract phone. I app**** via Vodacom and I was certain that my contract supplier is Vodacom, only to my surprise that my contract is underwritten by Homemark when I was querying amounts being deducted from my bank account and also why I am being charged more than what was agreed upon my contract??

Both companies do not want to take responsibility as when I contract Vodacom they say I must contract Homemark and visa versa. I'm really despondent to the way my query is being handled.

I need answers, if my query has not been attended to in the next 24hrs. I will have no choice but to cancel and stop the debit order and report this issue to further.

A contract cannot be amended after an agreement has been made.