Well at least as least it is clear now.
Phoned BT and said I would be happy to take their renewal offer if they updated my equipment to a Smarthub 3 + 2 extenders. The guide went away and when he came back - apart from trying to move us to EE for current price (ignoring the discount I had been offered from BT) - he said that the smarthub 3 would be ‘rolled out gradually’ but could not give me any timescales.
I told him that was a dealbreaker (the deal he was offering was the same as I could get online) and that was that.
He did offer me a Smarthub 2 as ‘that is on your account’ which would be pointless given the whole reason I was calling was because I already have one and it is old tech that needs replacing.
BT seem blind to the stupidity of expecting people to tie into a 2 year contract using kit that is already well past its use by date without any binding commitment that will ever change. The fact that they are also offering 900Mbps upgrades again without updating equipment to WiFi 6 is even stupider.
A few years behind mate. Some routers already do Wifi 7
..including the EE Smart Hub 7 Plus that I bought (new) on eBay last week for £25.
Doesn't address the repeater issue of course, and I can't use the EE app since my contract is with BT.