Bad service after i switched from LTE to Fibre with Telkom

I have been with Telkom for years and recently upgraded from LTE to Fibre. Telkom suggested I use Vumatel through them. I agreed to an amount of R699 per month with Telkom. My billing is incorrect and they do not want to assist to change to the correct amount agreed upon. I have never had such bad service and that after i have never had one returned debit order on my side. I have always been a loyal client.