SUPERSONIC PATHETIC SERVICE

I have recently moved into a new flat, and the previous tenants cancelled their Wifi with Supersonic in the beginning of June 2020. This line has still not been released by Supersonic, which has now caused the hold up on my WIFI installation, for which I've now been waiting 6 weeks for. My service provider has contacted them, I have phoned them on Tuesday, and Wednesday, and have also emailed their cancellations department, and still have not received ANY feedback. I do not know what to do anymore, as I can't spend hours on the phone each day, mostly holding on, and then just getting told they will send a note to the cancellations department. This is pathetic.