****ming people to pay for a service which was never installed

They claim I owe them money R2000 and some odd rands for Fibre service which was never installed. They keep on emailing me stating they are going to hand me over to there debt collection team and on each email they are sending me I reply to them to please provide me proof of installation + the date it was installed. (As I have cctv footage that there was no one to install because my premis is access controlled) + Job card + Detailed usage report on the PPPOE. Then they reply that they " Thank you contacting the RSAWEB Service Desk.

I have forwarded your request to the relevant department and you will receive further information as soon as possible.

Once again thank you for your time and understanding. "

So how can you say RSAWEB say if they can not provide proof. Then it means is they are trying to **** me out of money. I will not pay it because they never provided an line or a service.