Canceling the contract early

How to cancel contract when o2 didn't deliver their part and I was postponed many times ? 

Hello, I was promised internet on 29th November, didn't work. They said they'll send a technician, the company that contacted me made 3 appointments (07.12 ,09.12, 11.12) 2 times they couldn't come (I've wasted my time and vacation days for being home and waiting) the 3rd time the technician didn't even want to come because he doesn't have a place to park close ( he could pay for the parking ticket) and in a free zone the van was too far away (500 meters) and wanted to make a nother appointment.

After he begrudgingly came to check he stated that I cannot have internet through cable as I don't have a TV Cable.

After that I wanted to cancel the contract because I still don't have internet and when I called they said that they checked and see that I have internet and is working... 

I called and asked about canceling the contract but they first have to get the information from the company that came, they said call again after 2 weeks because they will get the information then.

After 2 weeks I called and they said there was nothing wrong and if I want I can send a letter of canceling the contract (Wich I did and was delivered on 03.01.24).

I've yet to have any response except that they ignored the contract canceling online and sent my Ticket to another technician again and again without contacting me at all. 

Ticket number is XXXXXXX.

The contract is o2 My Home M (cable)

Edit o2_Cora 13.01.24: Ticket number removed