Being told I am no longer a customer and need to return my equipment soon even though I'm still paying

Hello, Xfinity keeps emailing me to return my router since I'm no longer a customer with them. But I still am I haven't cancelled anything, still pay monthly for my plan and router so why am I being told I'm not and need to return my stuff? I contacted support and they said don't worry about it they'd fix it, but I was still emailed and called the next few days to return my equipment soon or I'll be penalized.