Disappearing airtime

I got an mtn sim in march because most of my relatives are on mtn so thought i could save. But I regret that as i spend now more on mtn than i would on the other carrier i was on. Since been on network i recharge and get \wow bonus"but from my own airtime is gone with it<br> The next day. Yesterday 25 May 2015 i got transfered R5 airtime in the morning by my husband and with it i bought 20mb daily and was left with R2 airtime then i was on whatsapp and<br> I did not recieve pics or videos i try to make a call and im told to recharge check my balance was now 0 and im not subscribed to anything 2hrs later im recharged by my husband with R30 air next day which is today 26 May 2015 i check my balance which is now R3.89 and i didnt make a call or recieve vids and pics on my whatsapp. I then bought another internet daily of 20mb and was then left with 0.89 i then called him then was left with 0.63 and he has recharged me now with R15. Im afraid it will also disappear so been on the line waiting for available consultant from 8:10 to 8:55 am and no consultant is answering. Please can mtn stop *****ing my airtime and can they atleast answer calls at their callcenter person cant hold for 20min """