PAYING FOR A DEVICE WE DON'T HAVE AND A CONTRACT WE DON'T USE AND NEVER SHOULD HAVE BEEN ADDED TO OUR ACCOUNT IN THE FIRST PLACE!

My cellphone contract is on my husbands name. Last year I was due for an upgrade and did the online upgrade. First had some problems but eventually I was able to submit my upgrade request. Delivery for my new device was scheduled and it was delivered at my husbands place of work. It was the correct device, however bit strange but something that has happened before with an upgrade, I got a new simcard. When I inserted the simcard we noticed that it was a new number, so they did not register the device as an upgrade but as a new contract. The next day my husband contacted vodacom to inform them of the mistake, all apologetic, confirming that they cancelled the contract as it was a mistake on their side, did the upgrade AGAIN and scheduled for the device to be collected and the upgrade device to be delivered. The device was collected a few days later and I got my new upgrade device. We knew that we had to pay a bit extra on my contract for about three months, so when we noticed the installment being more than it should be we were not concerned, however after a few months the amount still stayed more than it should be. We contacted Vodacom and their confirmed that we only have 6 devices, however there are 7 numbers. We queried the extra number and they kept on insisting that we only have 6 devices which means 6 numbers. My husband went in to a vodashop with the printout of the numbers and asked them he wants to know what that 7th number is that he is paying over R500 for. They then confirmed it is the device that was collected for the new contract that was added to his account by mistake, however they are NOT able to cancel the contract we have to pay it until the contract expires. The device was collected, we don't have the device, but we are paying for the device, they confirmed when fixing the new contract to upgrade that the new contract was cancelled, however it was not, so we are paying for a contract that we are not using. So basically we are paying for a device we don't have and a contract we don't use and they just pull up their shoulders and say they can't help us. We have proof that the device was collected, but no one wants to assist. How is it right for us to pay for a mistake that was made by Vodacom?!?!? I would really like someone to assist with this. How things are today, R500 is a lot of money, specially if you don't have it or is paying for something that you don't even have.