MTN Breaching contract

I signed a upgrade at the end of november, i was supposed to be getting 20gigs a month, instead i have been getting 500mb and no 20gb bundle. everytime i call in, the agent says they have escalated, few days later the ticket closes, i call again they say it was esacalated to the wrong department thats why it was closed. they open a new ticket and escalate it again, few days later they close it again. while MTN is closing tickets without it being resolved i am still being charged the full fee, i also have to purchase data every month.