Charged for a service that I was not using

I have been a client of Afrihost for more than 10 years and they billed me for a service I did not use yet and do not want to refund me.

I had an existing LTE service with Afrihost which I wanted to cancel and sign up for the fibre service. I did not want to be double charged and asked if the fibre line can only be activated once the LTE was cancelled, which was due end of the month.

I was informed by 2 salespeople that I will only be charged once the router is active. This is NOT true, once the fibre was installed they immediately charged my account, I have not even connected the router yet!!

Now they are saying that is not possible and I will be charged once the Fibre is installed and activated, NOT the router.

I have all the correspondence on email and WhatsApp where they confirm that I will not be charged.

I am seriously thinking of taking this to small claims court.