Weedman review: They have threatened me to contact a collection agency

WeedMan has called me this summer that I should pay them for the lawn care services that they had provided in my previous home address when I used to rent last year! I have never ordered any products from them or signed any contract with them. Even I was not aware of the existence of such company until they called me this summer! Amusing enough that I did not even receive any bills when I lived in the previous rental house!They are such rude that now, after several phone calls, they have threatened me to contact a collection agency!How do you reckon I should get rid of this scam company?!