mtn incompetence

Loaded 1 gig pay as you go data, 1 month package at R85.00 on 20th august. My balance thereafter was 3.68 gig Yesterday at 12 noon, all my data had vanished, 23 august. Mtn store, tablebay ball could not explain where the data went/ usage thereof. It just disappeared. My 1 gig, lasts an entire month, with left over, as I have wifi at home, and seldom use mobile data. Telephoned 135 yesterday , spoke to Kenzane at 15.36, and after repeating my problem twice, informed me that system was down. Mtn service is abysmal, and ***********, and she obviously was too lazy to sort out query, or was incapable of doing her job. MTN, please explain where my data disappeared? Please tell me what MTN stores are there for? Cant sort out a problem? Are they only there for sales? I await a response to this query? Debbie Peter