Telkom constantly Eating my Data

Telkom has been eating my data like crazy. Over the weekend i was in mpumalanga Leandra to be precise in which there was no network coverage for most of the time so I didn’t use my phone that much for internet or phone calls. Before i left Gauteng i had bough 500mb which was friday on Saturday i went to Secunda which the coverage is not so bad and received a notification say my data has ran out so i bought another 500mb still didnt use much of my data. Yesterday was the first so obviously my monthly data came in and yesterday even I received a message saying I’m left with less than 100mb ?!?!? How and now i don’t have data at all whilst I’ve been connected to wifi for almost half of today. THIS IS NOT THE FIRST TIME SUCH HAS HAPPENED. I have reported it several times and still nothing has been done nor checked