Phone Upgrade/Device Payment Plan Issue

I’m looking to upgrade both of my Xfinity mobile lines; however, I keep receiving a message stating “Your account is already at its maximum number of lines for device payment plans”.  I don’t see how that is possible considering that I have fully paid off the device on one line and the other line was a “bring your own device”.  I have always paid my bills with Xfinity and never had any issues with upgrading before.  After reading a few other peoples’ comments having the same issue, I came across someone that said to contact Xfinity Mobile Executive Solutions.  Can I please get some assistance with whatever this device payment plan issue may be?  I’m really needing to upgrade both lines ASAP.  Thank you in advance for the help!