Contract changed unilaterally for data

I emailed the following to Customer Care on 16 January: Please can you assist with my billing. My business is a former NashuaMobile customer which has been transferred to MTN by that provider. I notice in my first account the following discrepancy wrt the bill for the above number: I was on a 250 MB data bundle at R51.75 excl per month. I see that this is reduced to 100 MB on MTN, and the data used over and above the 100 MB appears to have been charged for. What has happened to the other 150 MB?<br> <br> Also, the phone/account is blocked to international calls so how is it possible to incur a cost for an international call or sms?<br> <br> I've been billed again for additional data in February as well - and I've followed up on 12 and 18 February. No response. PLEASE CAN SOMEONE SORT MY ENQUIRY. <br>