missing data

my name is yanga i have taken a cell phone contract with telkom direct on the 09-03-2015 for which is now im not happy with my contract,i keep on loosing data because of the network roaming to MTN agreement between the two parties i have lost about 190 MB so far when the network goes to mtn it will take forever trying to load the content and in the process im loosing my data..what can i do to solve this problem in the near future????<br> <br> <br> Kind Regards