DSL account and internet issues

I have had account and connectivity issues with a migration from LTE to Uncapped Fibre. DSL was the service provider through Telkom.

Issues are still unresolved and it has been almost a year since the migration contract has been signed.

Two months of very low to no connectivity and had tp pay my account every month. My LTE account was never canceled (migrated) and debit orders remained going off my account every month for about 4 months. Plus I had to pay reconnection fees once they sorted the low to no connectivity issue.

Telkom/DSL has provided me with one month refund in good faith but I feel this is not fair due to paying for almost 4 months on my LTE contract, trying to use my Fibre with low to no connectivity and being trying to resolve the issue for almost a year.

You have no leverage. If you don't pay; they just switch off your internet and request full payment before switching it on. Plus they charge rent on late payments.

DSL is shying away to pay anything and only pointing the fingers to Telkom. Plus they don't follow up, you have to remind them continuously that the issue is not resolved, request feedback on the cases log, etc. And the worse of all is I'm dealing with the sales manager and the service manager. No consequences for bad service?

I have requested that if they are unable to solve my problem, they just cancel my contract that I'm allowed to seek a different service provider to assist me.

Basically I have been trapped in a 2 year contract with additional payments, without full capability of internet and one year without resolving the matter.