Disappointed n irritated

Hi I'm very disappointed n frustrated I recieved my airtime on 12th August and agian I recieved on the 12th September and agian I eecuvrc on 12th October on the 5th of November all my airtime was depleted as told by boniswa the call center lady what I don't understand is why was October airtime depleted it's not yet 3 month for it to be depeletd how is that possible and so many times I complain bout the network in the area and they are doing nothing bout it yet they got time to rob me for my airtime and furthermore requested for a manager to phone me nobody has phone yet to date. I can't wait for this contract to finish with mtn so that I can port to vodacom or telkom.