The worst service experience of my life

The first problem is that the contract was sold to me under false pretenses. I was told that it was an upgrade to an existing contract, but when I started being billed, I saw that it was a new contract altogether - something I explicitly told the original agent I didn't want. When I contacted Mondeo Mobile, they launched an investigation, settled it in my favour, and gave me the option to cancel the contract, which I did. So far so good. Except, that was two months ago. The promised courier who would collect the device never came, and I am still being billed for this contract that I do not use. Vodacom, who is my service provider and on whose behalf Mondeo Mobile sold me this contract, has been profoundly unhelpful, claiming that there's nothing they can do, I have to sort it out with Mondeo Mobile. For their part, Mondeo Mobile is almost impossible to get hold of. I have written a letter of complaint - no reply. I have phoned at many different times, have been put on hold for at least 10 minutes at a time, and more than once had my call disconnected the moment the call centre agent finally picked up. When I did eventually get through and spoke to an agent, I asked him to please call me back in the event that the call gets cut off, so that I didn't have to be put on hold for another 10-15 minutes. He responded that he won't be able to do that, since they are a receiving call centre only. As if this isn't bad enough, the soundtrack of the music they play while you're forced to stay on the line is SEVERELY damaged, to the point where it is torturous to listen to. I have brought this to the attention of the agents, but in the more than two months I've been phoning them, nothing has been done about it. The only information I have managed to get out of the call centre agents is that there is apparently a delay in collecting devices from canceled contracts. I understand that things go wrong some times, and I understand the concept of skeleton staff over the festive season, but TWO MONTHS? This started long before the festive season. The last agent I spoke to advised me not to escalate the matter, since this would move my collection back to the end of the line. It makes absolutely no sense to me that escalating a query actually slows it down. What kind of a system are they running? This has to go down as the worst service experience of my life.