account suspended

the contract that i have is a top up, meaning that I pay R249 per line for what ever amount of data and airtime, once I have used it all, I load my own, as I wish. I pay R500 every month for the 2 line, never more, never less, now my lines are blocked, cause I went over my limit for some reason. I phone customer service, who could not explain why, who promised to phone back in 48h...till now, no one phoned and by lines are still blocked. My one phone does not have sound, I gave him in at volksrust branch on 30/10/2015, till now nothing from them, no phone and maybe feedback if you go to the branch and put up a fight. this is very bad service and I will not recomend mtn to any one.<br>