Vodacom reneging on agreement.

So after a running fight lasting for months regarding accounting discrepancies on a Vodacom contract, I just gave up. I enquired if it was possible for me to cancel the contract. Vodacom graciously acquiesced on the condition that I pay R7,500 before 30 November. This was done on the phone. I repeatedly asked that if I paid this amount, I would be allowed to cancel the contract. The repeatedly confirmed that this is the case. Fortunately I recorded the conversation, because, sure enough, now Vodacom is reneging on the agreement. They now insist that I pay R22,000. No surprises, then, taking Vodacom's low regard of their customers into account. Is Vodacom the worst company in South Africa to deal with?