MTN refund - Incorrect debiting date

MTN has debited my account on the 15th instead of 25th and i never changed my details or given them permissions to do so. I called to check what could be the problem and that they should refund me. I was told i should wait 2-24 hours which that lapsed on the 19th Sept. Today i called and i was told no feedback as yet and the agent was very rude. She didnt want to give me a chance to ask questions. She says wait for the email and that was it. Bad service from the provider and its employees.