Mtn will sunction your airtime

My airtime always disappears everytime when i load it using my bank app,this happened only now in january I tried calling mtn and thier consultant told me i have a subscription since 2016,i was not aware of that because during 2016 my airtime was not disappearing, and then she promised me that she cancelled the subscription, i loaded airtime again and then it disappeared, i called 135 and i was told by the second consultant that i could have waited 24 hours, i told the second consultant that the first consutant did not tell me that, so since i have been loading only airtime lower than 10. Now i have loaded a 35 rand airtime,i recieved a message from mtn saying my recharge was successful,only to find that when i make a call i will hear you have insufficient funds,i checked balance and it is 00, i called 135 and the consultant teld me that it is very soon to help me because it doesn't show on your their system, i tried communicating with mtn via Twitter but they ignored me. I like mtn but i wont tollerate disappearing aitimes i might as well change network