Poor service and *********** staff

MTN deducted R500 extra early upgrade fee in March. The query is been going since 16th of March until today 05 July 2021. I have escalated the matter several times no one is willing to assist ?? on the 4th of June Ofentse advised that Rosette from Retention passed the credit note on the 1st of June and it would take 21 days to reflect. Today I called following up and the credit note, I was told that the credit note was never passed but they very quick to cut my calls when I do not pay. This is really unacceptable ??