Cencel contract

My brother went overseas last hear October and will not be coming back to South Africa. He had a contract with you guys that ended on May 2015 already. He sent a letter to Head office which he got on your website. My Dad had to go and pay his account for him because apparently you guys never got his letter. So my Dad got permission with his ID and my Dad's ID to go to MTN outlet to cancel his contract. They said to my Dad that they can't help he needs to go to Head office or to a direct link of MTN. So my dad went to Kolonade MTN no they can't help he need to go to MTN Menlyn and guess what they also said that same thing .So I went to the same outlets my dad went and they said the same to me. So now I'm asking you what the hell I am supposed to do to cancel this contract, because your outlets are useless even the Managers working there don't have a clue what they are doing. And now they want us to pay R1500 because the contract is outstanding. So I won't pay this money because this is **************** from you guys. If i have to i will go and consult with my lawyer to get this issue resolved. So i am waiting for your feedback.