BT do not provide or maintain the external network. This is done by Openreach who work for all service providers. BT do not get any special treatment.
Delays are often due to issues between Openreach, and the builders. There is not a lot BT Retail can do about this.
If your order is being placed with BT Retail, then its possible one of the forum moderators may be able to help.
Welcome and thanks for posting. I'm sorry there's been a problem with the order. I'll be happy to lend a hand and check what's going on for you. Drop me an email with your details. You'll get the 'contact us' link in my profile.