Mtn data ****

I walked into mtn beginning of June to get a data deal.. I purchased the contract and today I’m here after being frustrated with the call center stating my data deal is not what I purchased and that my contract is not loaded onto the system by the store - their special was 12G ( 8 at night and 4 during the day ). They state that is not my deal as I only get 2 daytime 2 night time - worst part the data they say was loaded vanished into air as they say I used 7 G in total within a day