Incorrect contact and false promises

My husband signed up for My MTN Choice 10GB in November telephonically where he confirmed with the agent that this is the contract that provides 40GB day and 40GB data and that he will be debted on the 25th of every month. The following events followed: - We noticed that the debt order went off on the 31st instead of the 25th December and that the debt order was incorrect and enquired with mtn on the 2nd of January. -My husband was told that an investigation was started and that they would refer to the recording - He was promised that should he be found to be telling the truth they would need to cancel the contract and a new one would need to be signed with the correct details. - Mtn reverted back to my husband a few days stating that they were wrong and the agent indeed signed him up for the 5GB plan instead of the 10GB contract and she incorrectly set the debt order date. - They advised that he had to go to a mtn store to cancel the contract. - My husband then went to the mtn store in southgate mall on the 7th January where he was told that it needs to be done telephonically and not in store - He then called retentions to cancel on the 8th January where he was told they couldn't cancel or amend the contract. -He then escalated the matter to the manager on duty M. Zulu who advised that the contract would be amended and that he wouldn't need to cancel the contract. - They advised that the correct data would be credited to the account on the 11th January as that is the contract date. - The data was only credited on the 12th January where it was only credited with 20GB. - We would like to cancel the contract entirely and mtn can arrange a courier to collect the unit.

Regards, Mr AR Griffiths