As this is just a BT Retail customer forum, which has nothing to do with Openreach, nobody would have any Openreach contacts. That would be the same whichever provider you used.
As you are not an existing BT Retail customer, this is just really general discussion.
As you have not started building yet, there is plenty of time to deal with Openreach. I expect they are busy, and will eventually respond.
Use the "track account creation" tab, at the top of their page.
https://www.developers.openreach.co.uk/developerportal/index
