“Over the total number of lines" error message?

I have been trying for months to upgrade my phones which I brought to Xfinity from Verizon paid in full. Initial representative told me it would be best to port numbers prior to upgrade but since then I have been hit with the same error message repeatedly. I have no lines on a payment plan yet it will not let me check out due to recurring error message that I am over the number of set lines on a payment plan. Please advise and assist with this issue as no one via chat or phone can resolve this.

Thanks!