Returning deactivated equipment that is not listed in the Digital Return Center

I activated a new Internet/Voice Modem.  The EMTA I had rented is no longer listed in my equipment list.  Because of Covid-19 I cannot return it at the store.  My equipment is not listed in my account, so I cannot select it to start the return process.  How do I return the equipment and stop rental charges?

I need solid, accurate, and helpful advice to solve this issue.  Please do not direct me to the Digital Returns Center; the piece of equipment is not listed, which means I cannot select it to generate a UPS label. Please do not direct me to another thread in this forum  So far all I've seen is "I have this problem too" and "Doesn't anyone have an answer?"