Overcharged me and then waiting long for statement

i have a contract with a limit of a certain amount of gigs a month, the amount i pay for monthly. last month i noticed i could not go online and found out account was suspended, apparently i went over and spent a rediculous amount of Data(adding up to a too much in Rands), other than the fact that i obviously cannot afford it, i have been asking for my bill so i can see why they are overcharging me, called last week they said within 5 days, then i called yesterday and they said 24hours, still waiting. I've been speaking to friends and it may be that i have that type of contract that goes over whatever amount of data you have left but in that case i should have been told and i should have had the option to put a limit on it. I have had numerous contracts with MTN and i would like to stay but if it turns out i am being ****** here, i will close any all contracts and contact with them.