Historically Plusnet have never seemed to like simultaneous provide migrations, and nearly always migrate the phone before
placing the broadband order.
Ask support to check with the "Provisioning team" what is going on. (Though I expect first-line support haven't heard of them. Only the forum reps will).
Kindness isn't going to cure the world of all its awfulness but it's a good place to begin. Daisy Ridley.
My broadband basic info/help site - www.robertos.me.uk.
Domains, site and mail hosting - Tsohost
Connection - AAISP Home::1 80/20. Sync 54999/14466Kbps @ 600m. BQMs - IPv4