Extremely bad customer service and response from Vox

I ordered an upgrade to my existing 20/10mb fibre line early in January, and having waited a few weeks and with failed attempts to reach Vox telephonically I sent an email on the 30th of January to cancel te order to upgrade my line. I received no reply or feedback from them and my line was suspended due to an outstanding balance. I sent emails again and they rectified the problem and my account balance. I also spoke to someone who suggested that I downgrade my line online to avoid further billing and even that order has not been completed to date since the order confirmation on 7th of february 2023. They then moved my line back to a 100mb line and started billing me for the outstanding amount again. I have been sending emails almost daily to every email adress I have together with failed attempts to contact them tellefonically as the lines are constantly conjested/crowded, and they still have not contacted me. Now my line is suspended again and they are billing me for a new months service on a 100mb line. Today evotel contacted me as I am changing ISP's, and the lady said she will ask Vox to contact me urgently (priority phonecall) to confirm cancellation as I am unable to migrate my line to the new ISP. I have still not received any phone calls, let alone emails from them. I want Vox to cancel my service with them and release my line so I can change my ISP, and I cannot be help accountable for the outstanding amounts they are billing me.