I tried multiple chemicals including Comet to remove it, but didn't worked.

Living in Canada with harsh winters is that something that could break a deal for anyone?

Most exterior cap ex items last longer in milder climates than harsh climates resulting in lower long term costs. 

Do you guys have your cleaning service take care of rhe cleaning and chemicals?

I have also asked her to send me information of what chemicals she used to bomb the unit as well as dates.

Cheaper options include using chemicals like Odoban or trying an ozone machine to clean the area.

You couldn't be bothered to use a 50-year-old weed control chemical on an overgrown yard because you believed some quack somewhere that told you it might cause cancer.Now you're hypothesizing that your dirty tenant brought a breeding population of rats with him.Come on, Peter.

I live in the CENTER of 6 major chemical plants including BASF, Dow ,BP... the rental market here is KILLING IT, because you have the average Joe making 75-125k a year!

@Justin FranklinTry reaching out to Shawn Huss from Chemical BankYou should be able to find him if you Google.

Click bait" is pretty harsh.