DKS has a monopoly on air/heating services at some condo buildings in a N. VA area. In one instance, one guy named Dana gave me an estimate for an appliance that was $300 over competitors. Then I call again to get a quote that was much lower. The agent on the phone couldn't explain Dana's behavior. I did find out that Dana was due to retire, so I can only assume poor memory recall on Dana's part. In another instance, DKS sent someone over for heating repairs and charged me $450 and claimed it was highly involved wiring work. I found out from my tenants later that all the DKS technician did was turn on a switch and left after 10 minutes. Each time I had to deal with them, they were over 30 minutes late.