Marshall Mechanical Changed estimate, multiple poor repairs Richmond Virginia

Have used these guys for multiple properties over the last couple of years.  Initially put in central a/c for me and did an OK job--they were prompt and clean, which was enough to get me to use them again.  I noticed a year later that I developed a roof leak--the flashing around one of the penetrations flexed and broke.  At another properties I had a freon leak.  

First tech came out and said the most likely explanation was that my tenants were huffing the freon.  He refilled and it was gone again in a week.  I came out with the second tech, and saw an obvious leak (oil everywhere) in the condenser where some tubing had rubbed and developed a hole.  

Called them once to fix a boiler.  They fixed it, but charged me for 5 fuses at $30/per.  Last straw--my 2.5 year old central a/c unit leaked.  They charged me $350 to diagnose a leaking coil.  Quoted $575 (or thereabouts) to repair.  When they arrived, the quote turned into $1250.  

Tried to contact someone about that for about 2 months.  Never got a return phone call.  Finally talked to someone there and was told that I was "misquoted" initially.  He offered to do it for $1150.  No thanks.  My fault for sticking with them for so long, but at least I had the chance to get a good sample size.