data depleted

Good day I am very unhappy with the feedback i got when i called your call centre Saturday i have a contract which expires next year in july and i am sure that i will not upgrade because of the service, i get 100mb of dat on my 084 number and 500mb of dat aon my other sim card but on the 1st the day it was loaded my data just got depleted i then called and i was told that it was my banking app but there is no way my banking app there is no way my banking app can deplete 600mb i then asked the consultant to load 1gb but at 4pm that too got depleted

please fix this i need my 1gb data i cannot pay for something i did not use