Disapointing service

I took a month to month contract to cancel at anytime. I cancelled in July 2026 and they sent courier to pick up the router to finalise cancellation. Its been 4 weeks since the router was picked up and no one called me to finalize the cancellation. I am now getting calls that I owe. How reficulous is that, and when I ask if the consultant that called me if they got the router, I am told she does not work with courier. Why then call if you dont have the full facts.