Additional Billing Due to Own Network Error

I have a router/wifi contract with Telkom Mobile, which I normally pay R150 for. However, for the month of Jan 2021, I was billed R558 because apparently while I was using the router, their network changed bands and deducted the data usage from my airtime and not from their monthly allocation of 10GB. This 10GB was never depleted. To make this worse, on the 1st of Feb 2021, I was not allocated my 10GB, when I queried this, I was told that my data had depleted, but my router was never on since mid-January 2021. I refuse pay extra for their network that decided skip bands & cause out of bundle use, this was even without notification. I want my R350 back please.