Pathetic service

I recently took up a new contract with MTN, but I never received my 20GB once off data. I called them on 25 May & a call was logged. I then left it for a few days, then I called back but their system was offline & they said I should callback after 2 hours. I called back the same day, then the consultant told me they looking into the matter & that someone will call me back- that was last week. Still no callback received. Today I phoned them again at 2.30pm & the system was offline again. I asked can a manager call me back the same day & the consultant said he would assure a manager calls me before close of business. I still haven't received a call 😡😡😡😡