Worse service ever

MTN Vincent park East london has the worst service ever with their non-chalant staff. I had a month-month home router which i cancelled and return the router yo the store. MTN kept debiting my account several months after i had cancelled. I kept going to the store and there is just no accountability,zero customer service from their manager down everyone is just non-chalant. When i called MTN customer service they are saying the store is at fault as they have not emailed the required documentation.