Openreach supply all service providers apart from Virgin Media.
Is this a new bulid house, or an old property that has never had a phone line?
Two options, but you are unlikely to be able to change the appiontment, as BT Retail have no control over the date that Openrech specify.
Try the Order Live Chat Team
Monday to Friday 8am to 8pm
Saturday 9am to 6pm
Please have your account number ready (it’s on your bill).