Century Link Billed for Unreturned Modem Seattle, WA Washington Nationwide

We are a military family that was stationed in Utah and had Century Link for 3 years and leased our hi-speed internet modem...very good credit, no issues with the internet service on either end until now.

We moved cross-country and went into a Century Link store in Murray, UT to return the modem and instead given a pre-paid label to ship it via UPS which we did. We held onto the tracking number until 3 weeks later when we noticed it had arrived to the Century Link location (don't recall the city).

We called to confirm with a customer service rep who while looking up the number had his computer crash (suspicious?). In the middle of the rest of our move, we shredded the tracking number and thought that was the end of things and that we were hypervigilant on making sure  the modem has positively changed hands.

Last week (October 16), we get a bill for $106.84 for an unreturned modem charge. I challenged Century Link over 2 phone calls and we are at empasse. They will not help you unless you have the tracking number. Ridiculous business practice! I told them this can't be the first time this has ever happened and they admitted it happens about once a month which is hard to believe. 

Century Link are gouging customers for unreturned modems and seeing the other posts with the same problem makes me seethe in anger!