Poor service

I downgraded my prepaid subscription from 400 to 250, my wife unknowipaid 400 on the 27th December the vooma Fibre worked for a day and as soon as I brought to their attention that I was overcharged I got disconnected. My wife has been logging complaints seeking for assistance from the 27th December to date she's been told that the matter is escalated and haven't been given any feedback, we just called vooma and we're detailed that our subscription is canceled, the question is how and why is it canceled without getting informed and any feedback concerning our inquiry/ rather complaints.