Bad experience that left my credit score dented

Good day

I am writing this with huge disappointment with MTN. Last year September I received a call from their agent offering me a unlimited home router for R295. I agreed and took the offer. Used the router for a month. Statement came in of what I had to pay and it was way more that what I agreed on. I phoned MTN countless times, agents saying that I was given a router and a sim card loaded with airtime.

Which one I was never offered no sim card with airtime and I never received and used no sim card with any airtime from them.

I phoned countless times. I was told to report ***** to MTN which I did.

Till this day I was never helped. From everyone that was assisting me promising to get back to me.

I was then handed to legal accounts, which I also asked how was I supposed to pay a bill that I was not liable for.

To this day I have a big bill at MTN and they have ruined my credit score.

I regret the day I agreed to take that home router.

Please assist.