ALL I WANT TO DO IS DOWNGRADE. HOW DIFFICULT CAN IT BE!

I have never been met with such incompetence in all my life. I wold like to downgrade my fibre line as I am no longer working at home. I went onto your the web portal to do it online (as I have done so in the past). When I tried to do this I get a message that they are unable to do this and that I need to phone the sales team. I have phoned 3 times and EVERY time I reach a sales consultant who tells me I need to do it online. I then explain the message I received. They then say they need to put me through to another number. When they put me through (all 3 occasions) I get a message "Due to unforeseen circumstances we are unable to take your call. BEEP BEEP BEEP". All I want to do is downgrade my account. DOES IT NEED TO BE THIS DIFFICULT? What do I need to do to downgrade the account or should I rather cancel?