Just Mowing, Erie, PA Did not complete work contracted to perform Erie PA

Contacted Just Mowing to do fall lawn mowing and yard clean up.  They quoted the job, we agreed, they came to the property mowed, only cleaned up part of the yard, left piles of leaves uncollected and other areas of the yard they made no effort to clean up the leaves.  We only paid what we believed the value of the work they did.  They sent us a letter asking for the balance, we called their number 3 different times, left messages, explained in the message why we didn't pay the total amount, they never called us back.  We stopped at their "place of business", which is a carwash, dog wash, and laundromat, no one was ever there.  18 months later (Aug. 2018) we get a nasty letter from them stating they are going to turn us into a collection agency, they sent a copy of the county assessment of the property where the work was done to intimidate.  I would never recommend or use these people again, they are unprofessional, don't return calls when you clearly state you are not satisfied and then use threats to try and resolve the issue in their favor.