First Time Financing Device - Zero Lines Avaliable

i’ve been with xfinity for 3 years, and first came in with my own phone. i am trying to finance a new phone through xfinity, but am given the error that i am over the limit of lines i can have on device payment plans - but i only have one line, and no current or past payment plans. i have very good credit, and they have taken my social multiple times without seeming able to pull a credit report (?) but it is very unclear to me what next steps are to resolve this. i changed my plan to mobile plus to be eligible for the new device promotion and it has been nothing but issues!