Try ringing them out of office hours. I had the same problem with British Gas. When I did eventually get an answer, the person at the other end recommended that, next time, I ring out of normal office hours.
I had to do this last week - I'd tried on & off all day for a couple of days, finally got through (on 150) to a brilliantly helpful chap at about 6:15 pm on Thurs.
He mentioned that it was *probably* (no guarantees, obviously) better to call in the evening. Just keep trying, Andy.
Thanks Tilly - that's the e-mail that wrote back and told me they were Retail and not connected to Customer Service systems, and to ring 150!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
APC - To be fair, BT Call Centres have a rolling 25 per cent sick record when things are normal, it is such a horrible place to work - I imagine with the option of 'self-isolating', the whole lot are at home!!!