As already stated , your arrangement with Openreach , not BT or EE or anyone else for that matter is between you and them , and of no relevance to this forum or the forum moderation people…if you are convinced that the Openreach original terms of connection should apply 5years later , you presumably would need to seek a legal opinion and legal action to get that applied if OR are insisting that the current terms apply as your application is effectively new , personally I think it’s unlikely that a free connection is still available.
I linked to the new rate card for developers , the old rate card was actually in some way worse for small scale developers as single plots and dual plots got no ‘pro rata’ reductions on costs that larger developers got , if you go down this route I suspect the charges shown are what will apply and TBH , although it’s not my place to judge what’s value for money and what isn’t , I suspect you paid far more for other essentials, what’s more these days there are multiple network providers, don’t like Openreach prices , try one of the dozens of other providers that install network.
FWIW , I suspect the new build process is now moot anyway , that process is for developers that include Openreach from the start of the development all the way through to plot call off , and are they guided through the requirements that OR need for connection to their network, your development is something of a fait accompli, as it’s already built and occupied.
I take it the address is registered already with the local authorities for council tax etc and has an entry on the Royal Mail addressing (Post Code) database
