Worst Possible ISP

I placed an order more than a month ago, but decided to go with a different ISP and cancelled my order with Supersonic before any installation took place and before my line could be activated. However, they are still holding my fiber line hostage, making it so that my preferred ISP can't place an order and activate my line, because they never cancelled my order. I have called multiple times every day for the last week, trying to get them to process the cancellation that has been requested a month ago, so that I can get internet to do my work, but their call center agents are useless and if they don't outright put the phone down in my ear, they tell me that there is a problem with the cancellation and that it's with their cancellations department and they can't help me. Any callback requests are ignored and they have kept me on hold for hours at a time. I have tried to be patient, but they are useless and I would never recommend their so-called service to anyone.