overcharging of loyal customers

I visited the fourways branch to querry my problem but i was told to call 173 as they were not able to help me.every month i get my monthly statement bill via email but end of may i didnt get one i hope mtn know why they didnt send me one.my contract is for 350.00 monthly and i dont exceed 400.00 as it is limited but i was surprised when mtn deducted 2500.00 frm my accnt what a ****************.why ??.i need a valid answer. Dont tell me i did overspend since i am on limited mega bytes.what does limited mean.please get this addressed and i want my money back.i wss told that mtn is on strike then who is going to help me???.get this addressed please as i feel ******.