I appreciate what you're saying, but I don't think that is the case in this situation.
When my parents got fibre recently - the cabinet was full initially. All the line stats were still there for FTTC even though the cabinet was full, and we could place the order etc - it just got wait listed on cabinet capacity. The www.superfast-openreach.co.uk
website also told us that the cabinet was on high demand and the order would be wait listed, so it seems pretty accurate to me.
With my line, www.superfast-openreach.co.uk
says that my cabinet (45) is accepting orders, isn't in high demand and everything should be fine, but when you put in my phone number in the checker it only displays stats for ADSL
Something else is broken - it's almost like the checker database isn't correct for the line, and it thinks I'm not even on an FTTC cabinet.