Bad Service and more

My dad got a so we thought was a pay as you go data as we had our own device and was told by the sales consultant this can be cancelled with a 30 day notice as it is preloaded bundle. from day one we have had a problem he loaded my dads bank account number with his id number and this took almost 2 months to sort out as they said there is no contract on the system. I gave them notice to cancel on the 20th of November did try prior to that and emails went un answered and then I threatened to stop payment until I got a reply. The retention department just ignored the request and when you call them they cut the call I have been dealing with customer care and the branch owner they now say I have to pay a cancelation fee as per terms and conditions on the contract and there is no contract I have requested the so called contract and no-one in mtn nor the branch can provide this contract that does not exist I have emails to prove there is no contract as i keep saying the sales man said there is no contract when we first app**** he said due to you not taking the devise is simply a sim card. please advise how can I sort this issue out for my dad he cant hear so he has given me power of attorney to handle this issue which has also been sent to MTN. I keep been told we in contact with the branch to get a copy of the contract the owner wont even take my calls anymore. Mandy Horn