I can only report what I was told. if you sent in a email it went to BT retail initially but was then rerouted. The email itself isn't much use as it just says it came from BT but doesn't state which area. the email address it came from was
[email protected] which doesn't mean anything to me.
My query was quite specific and maybe that is why I spoke to somone in Openreach, or if he actually wasn't Openreach he spoke to someone who was. I still have the initial email and could contact the guy to confirm who he works for, but I am not sure what value that adds. The real detail of the actual query wasn't answered by him but by someone else in Openreach and then passed to me in a phone call.
Possibly I was mistaken, but I don't think so, as I was surprised at how much time they spent on the query. Two 30 minute phone calls and several emails internally to confirm.
When you organise a promotion like this I don't see how Openreach can't be involved. When BT retail opened the competition to everyone clearly their own systems weren't going to be able to provide all the data they needed.
My query related to a large university/military base in the village. Number of lines quoted for our exchange exceeded number of dwellings by a large margin so some, but not all, lines on base were being counted. I wanted to know which lines were in and which out so campaign could be targeted properly and keep to the competition rules. With hindsight I now realise I shouldn't have been so precise. I should have just got anyone with a direct dial line on the base to vote. I would have got loads of votes very quickly and just taken a chance on whether BT retail eventually through them out in the end. I guess they probably wouldn't, and even if they did the initial massive show of support would have helped to get others in the villages to vote to keep us high up the charts.
Strictly BT retail and Openreach are separate but in practise such divides never are perfect in a large company. Individuals have contacts on the other side of the fence and will use them I have found. Obviously puts other ISP's at a disadvantage but not much you can do about it. ISPs can raise queries with BT themselves, via account managers or such like, and their staff often have contacts in BT anyway.
As to how BT retail gets FTTC out there your method seems correct. Presumably BT retail pick up the bill if take up is way below that required to cover costs as there are some rules about ISP nominated exchanges and take up rates required to avoid costs being passed back.
I may be looking in the wrong places but can find very little that explains how BT decides which exchanges get which services. I would have thought a regulator would be all over them to make sure they want using their control of the exchanges to abuse the market in some way but maybe FTTx is too new for the regulator/government to catch up