Telkom de*****ing me

So I took out a fibre contract with Telkom last year July/August. I then waited for almost 2 moths for them to come and install, I even gave up. Later around October they sent an sms that they are going to install the wifi route and I should confirm if I’ll available at the address, I then rep**** no as I was not staying there anymore. I called and asked for the contract to be cancelled as I never received the router but I was getting billed for all those months. I spoke to some useless guy who’s apparently a team leader and he promised me that the account will be closed because he could see on their system that I never received the router, but to my surprise I am still getting billed on a monthly basis and the amount keeps going higher and higher. Am I supposed to pay for the services and goods I never received or used??? I sent emails numerous times to the team leader guy he doesn’t reply. What am I supposed to do to get this matter resolved? Or should I go to the ombud?????