Returned equipment to Telus, but still receiving reminders to return.

Hi, I just cancel my telus home internet service on June 25 and I sent my WIFI model with my account information to telus with Canada Post on the next day. I could not print a waybill online because it keeps saying error, so I contacted mobile support and they sent a waybill to my email. 

the package said delivered on June 30, but I just received an email on July 25 and they say I didn’t return it, they said no record of return on July 10. 

can anyone tell me why is this happening? Is the package not processed by telus warehouse? I really don’t want to pay the fee for not returning the equipments.

if necessary, I can still provide tracking numbers, pictures that can prove I shipped it back.

Thanks for any help