Escalation due to no response from MTN

On 24/06/2015 I received an invoice from MTN Totalling R35041.90 (taking into account that my average spent for the last 6 months equals R1463.37 leads me to the conclusion that this is incorrect).<br> I called MTN's call centre (25/06/2015), spoke to Gregory Modisaotsile, reference number *** for a validation and URL Report, to be sent to me within 3-5 working days.<br> I logged a second call on 25/06/2015, reference number *** / ***8.<br> On Saturday (04/07/2015, 6 working days after both calls were logged and no response received), I went to the MTN store at Clearwater Mall. The assistant checked the reference numbers and confirmed that she can see the queries logged but it has not been actioned. She logged a new call (Reference Number: ***) and, according to her, escalated the matter to the Credit Department. I have not received an email to confirm this call was logged.<br> Please can you assist to resolve the above mentioned? I am trying everything in my power to get this sorted out but feel that MTN is not coming to the party.