Mtn
Mtn data contract

I have a mtn 2gb data contract @ R399 per month which stayed within the 2 gb limit until october 2013, after which it increase slightly and december 2013 i was billed R1399 . I have logged a complaint with the mtn service center USD 3216350 on the 02 February 2014 and after calling earlier today i was informed that billing queries can take up to 24 working days. My cellphone and data contracts come to an end this month and if this is the response i am getting i will not be upgraded any of my accounts. Please advise urgently on excessive cost and refund