Mtn over debited my ...

Mtn over debited my account, with the whole R700, initially one of the consultants told me it was a mistake and will be payed back, upon follow ups, I was ultimately told that extra fee was for a migration fee that I have never even approved, several consultants kept pestering me about the migration that I rejected several times and told them that I was due for a contract upgrade and I was not interested in making any changes to my contract, but for some reasons mtn enforced this package migration on me, and took the money that was meant for other important things, and named it a migration fee, I even regret upgrading my contract with them, as they *****ed me as their loyal customer, I want my money back