Vodacom refuses to help their clients!

I am very disgusted by the absolute refusal of Vodacom to assist in any way regarding a Vodacom contract!?!? My contract is under my mothers name and in February this year my mother received a call from a man saying he was calling on behalf of Vodacom with this brilliant deal she just could not refuse, a laptop and 5GB data for R399. He also mentioned extra data bundles offered but she was not interested in these deals as we both have uncapped Wi-Fi at our homes. She explained to him that it was her daughters contract but she felt I would likely go with the deal she just wanted to double check with me as I would be paying for it, he was very insistent that she take the offer immediately and she could always call him back. When my mom got hold of me I was interested i the deal but I didnt really want the extra 5GB data, she said she would call the number that called her back....no answer after repeated calls. I agreed oh well I will just take the extra 5GB as it likely is a package deal. Well about a week later my mother phoned to say the computer had been delivered. When I opened the package I saw there was two sim cards, confused I immediately called Vodacom customer care. I was told that there were two new contracts opened one a 5GB 36 month data as well as a 10GB 24 Month contract. I explained that noone agreed to the 10GB contract, I was then told "sorry we cant help you, you will have to get hold of the company that does the sales,Mondo Mobile". So Vodacom cant do anything about a Vodacom contract? Well trying to get hold of Mondo Mobile is another situation completely, it is not a toll free number and you hold on for an average of 20minutes and then the number just gets put down. I eventually got hold of them after weeks of calling ,for them to tell me they will have to do an investigation and will call me within 5 working days, 5 days came and went and then I began the process of calling them for weeks on end until a very rude lady answered. I gave my reference number and was told that the investigation was done and they were not willing to cancel the contract as a contract was agreed to that day. I explained yes one contract was agreed to but I just don't want the 10Gb and that I have never used it and I cannot continue to pay this. She just refused to help any further, I then insisted that I hear the recording and she put the phone down in my ear. I have been to Vodacom a number of times with the packaged sim card begging them to just to it back and stop the contract but "nope sorry we can do nothing". They can not hold me or my elderly mother to a contract we have not agreed to and the great issue with Vodacom is that if I refuse to pay the extra contract that I did not want and do not use they will stop all my contracts and Black List my elderly mother. This cant be legal!!! I feel ****** and helpless!!!