Harassment for paying for fibre I did not order

Vumatel and or their debt collectors keep on phoning me for money for an installation that was done. I'm the tenant and never requested the installation of fibre. They are unable to provide me with an order or quote of who instructed them to do the installation. Not very professional to do an installation without a signed order and now I'm being harassed for money. Best of all, I've given them the owners' contact numbers and email address and every time they phone I have to ask the same question "did you read the notes on the system before you phoned me"? The answer is "no' and then they continue to ask me when I will make payment. How ridiculous is this? I then have to explain the whole story to them again. One time when they phoned me the lady assured me that my contact details will be removed and she apologised for phoning me, this was about 5 calls ago. This is harassment and pure incompetence!