Currently the not so proud owner of a couple of medical collection accnts.  Has anyone been successful or had any dealing with either of these two companies, HOLLIS COBB ASSOC, INC or  AR RESOURCES INC.  I would appreciate any and all info, advice, etc   I want to do a PFD letter but feeling a bit apprehensive, I have never done one and don't want it to back fire on me

Begin; FICO 1/11 TU 672, EQ 654.......1/15 EX 649
Current; FICO 3/21 TU 709, EQ 677 ....3/26 EX 660
Goal 720 across the board