MTN poor service

i took a month to month home wifi, asked to pay prorata and advance for the next month, a month later i received an invoice with another prorata and the next month's cost which was double the contract price. when i enquired i was told the first amount was fees, but how can fees be the same as contract amount, very disappointed with MTN. and their service is also very poor for investigating issues, they closed my queries without communicating to me.