Disappearing monies

I want to tell everybody to stop using mtn momo, i cashed in from my standard bank vitual card and then i proceeded to transfer R90 of it to absa now it has just dissappeared into thin air when im enquiring they asking me for proof of payment, i mean why did they accept my money in the first place they sure have the proof of payment that they are asking me for Mtn is growing by exploiting the poor.