MTN Poor service

I have upgraded my data contract at the end of January, but at the end of February and March only received half the data I am paying for. I have been back to MTN Cradlestone on numerous occasions to log queries and the shop assistant also agrees that it's incorrect and phoned countless times. More than a month later, I am still awaiting feedback, Phone again this morning and no one even bothers to return my call after leaving a message for the manager