Vodacom contract accounts

I have had problems with vodacom with debit orders not going off, them using settlement payments I have made for installments and I continue to email and phone them, service is so bad, because no branch assists, Noone responds to emails and no one returns calls, as customer care are unable to sort this out when I phone. I am tired of struggling. I won't be held responsible f9r any arrears on my account, due to them not deducting when they should, where there is funds in my account. How to I go about canceling all 4 my contracts without been penalized, as this bad service is not my fault, and I am fedup phoning and mailing them about payments not deducted and where they use my settlement payments for what they feel.