With the Coronavirus situation there's a few issues and I guess it's due to lack of staff in certain department(s) at this time, particularly at BT Wholesale.
I did a regrade on FTTP with an ISP recently, not BT Consumer/Retail, and I was surprised when they told me it'll take 7 to 10 working days for a mere change in the speed. That was not long before BT's website no longer mentioned FTTP availability at my address and that BT Wholesale's checker for the address stopped working entirely. I also read recently that apparently BT Wholesale has an office in India that handles things like FTTP regrades, and that there's nobody there at the moment. Some others have reported delayed regrades with BT Retail recently, compared to the expected 24-48 hours that some early on received.
On another ISP's website, their checker is still showing I can get FTTP 1000/220 at my address interestingly, and they check with BT Wholesale and TalkTalk Business (TTB shows as unavailable which I expected).