Simple way to get them to stop. I sent them a cease and desist letter by registered mail. And voila! no more communication. Here is the Ontario template link. Just copy and add your info.
http://www.docstoc.com/docs/16640811/Cease-and-Desist-template-letter-for-Ontario-residents
MJR was calling me on behalf of my ex who maxed out a card after we divorced and after the 2 year SOL. (I was to cosigner) They called constantly for 3 days 5 times a day by their 4151 number and 2 seconds later by a blocked number.
It cost around 10 dollars to send a registered letter but worth the cost. I checked online at Canada Post. When they accepted the letter the calls stopped. So it worked for me.
One thing though; where it says Pursuant to my rights under ONTARIO REGULATION 103/06 write what I just pasted. It's been updated.
Hope it helps.