Awful Customer Service

I believe I now understand (mostly) what has happened here. Other users may find this useful. I have a data sim in a LTE modem. This sim is allocated 5GB data monthly on contract, no air time or anything else. My practice, if I run out of data, is to buy airtime using my mobile banking app and then convert the airtime to data using my PC. However, I have learned that, if I buy airtime after my data has completely run out, then any internet traffic consumes the available airtime at R2.00 per MB - yes, that's correct, about R2 000 per GB!!!!!! So woe betide if G-suite or some other app happens to be in the middle of a sync - there goes the airtime in a flash, boom gone, just like that. Why do I do it this way? Because 5GB data converted from airtime costs R289 and 5GB data bought directly costs R399. Only Vodacom could come up with such a sleazy low down way of operating! I have really struggled to get any sensible information out of Vodacom on this issue. The franchises are completely unable to help. The help desk hasn't a clue. The Vodacom Customer Care branch at Greenacres Port Elizabeth were the first ones that were able to give me a clue. R2 per MB - what a chee****