buying of airtime

Hi am a consent client of absa bank and am very happy with it, but my one consent is when it comes to buying airtime through cell phone banking, why would i buy airtime if i have airtime? So this system of us having to have airtime first before we buy airtime does not make sense to me and sure alot will agree with me, could absa please review this because alot of people are not happy with it and are going to other banks like FNB who offer this service free, please do something because i don't want to leave the bank but since i buy airtime alot through cell phone banking i would have no choice but to leave.