why pay for cancelled goods?

In Desember vodacom contacted me with a special package that they had on promotion. I accepted the offer thinking that my current contract will be upgraded to this package. When the package was activated 1 January I saw that vodacom sent me a complete new package instead of upgrading the existing contract. This was a misunderstanding. Now I had 4 contracts. I cancelled and returned the goods. End of the month my debit order went off and it was for all the contracts. I reversed the payment and only paid for my existing contract. In the week of the 7th of February my line was disconnected. The line that I payed for. After many many phone calls I found out that if I pay for the cancelled contracts, then only can vodacom cancel the account and return my money. Vodacom can not cancel an invoice before I pay for goods not received. This is unacceptable. Cancel the invoice! Connect the contract that I have paid for! How can you charge for goods returned and cut a line that has been paid??