Contact BT before the engineer's visit

[#1]

How do I contact BT regarding the engineer visit? My flat is in a housing association building and the engineer will need access to the internet cabinet. According to the housing association, internet providers know their procedure when visiting a housing association building and should contact them before the visit. It didn't happen with the last provider I tried to sign up to and I want to avoid it happening again this time. 

[#2]

My goodness, a customer wanting to contact Openreach (which is the successor to BT) about his connection? I'm afraid OR don't provide this facility, all requests must be routed through your ISP. I suggest you give Plusnet a ring and explain the problem as the help team rarely visits this forum.