Bad service

On the 24th of November 2017 I loaded a airtime of R30 and bought a 100 MB from that R30 so I was left R15 airtime and 100MB and it was finished within seconds for only using a single application called whatsapp ,I decided to stop any attempts as I've had this problem before,next day 25th in the morning I did the same transaction and lost the airtime and data bundle within seconds after loggin on to whatsapp ,and all other apps where switched off from my settings as I know from my previous complaints I made and I was told what to do in order to save my airtime, this time I was surprise that the problem of airtime disappearing is back and this time only one app is switched on,I called the service center and found Lindiwe with a high level of Bad attitude ,as I was explaining my problem she tells me that she is checking my profile and I should wait while she is checking my profile ,what makes me unhappy is that she did not allow me to give my full story and expects me to keep quite while she is checking my profile ,I told her that she is rude and rep**** that she is not ,thereafter told me that the airtime and data bundle have been used by my connection and as I arguing that how can a single message app take so much in seconds for just reading texts and not even viewing videos or photos, she told me I must check as if I don't how to check my settings and just told me thanks for using MTN as if she meant it and hung up the phone on me like I am her nuisance and I know for I am her customer . This tells me one thing that MTN is ripping us off and they have the face for *********** and to think that I've started using MTN in 2004 to date and this is how they treat me,Iam deeply horrified .