False promises - cancel account

I sent a change of address form on the 24th March 2023. The lady I spoke to over the phone told me I must just plug in my Fibre in the new unit and it will work, but it didn't. I made calls to Metrofibre on the 1st, 2nd, 3rd and now the 6th April. I have always been promised that a technician will come to help, but nothing. I even had a chat with their Instagram account and emails in between but they leave me high and dry.

I have all the reason to cancel their account without paying a fine. Otherwise, we'll fight in court.