Due to strike at mtn i have to suffer, rude staff!

hi there, i have called the mtn store in worc 18 times since 20/05/15 and they were busy with my query (they dont get back to you, you have to call them), and now the very rude manager refuse to assist in the matter and just keep on telling me its an issue between me and cornel and if he logged my queries i can take it up with him. Cornel has since left mtn and cant assist in the matter. i ran up a massive data bill because i was on an open plan, no one advised me that the contract was open i have always had closed or limited contracts. According to the store manager if on my invoice it didnt say topup i should have known its a open plan. this lana person said she will just tell me my queries would automatically we closed as it is not a valid query. she refuses to answer me of what the outcome was and i asked her to log and open it again she just said she cant and wont as it will just be closed again. she said i am more than in my right to call customer care and complain there as we know they are on strike and ill be on hold for about 4+ hours. I am more than willing to pay for my data i have used at topup rate but not at the astronomical amount it came to. ***