My old jump instructor, Samantha Allen, now runs Rossmat and I'm not excatly sure what she offers as far as lessons on her horses. I know she gave lessons on a mare of hers at one time, but I'm not sure if that horse is leased out at this time.
Nikki Vogel, who I used for dressage teaches out of Ross Matt on Wednesdays I think.
I don't have numbers for them anymore, been out of the loop for a little while. If you stop by Rossmat I'm sure someone can help you.
I really liked both of these instructors as people and instructors and would recommend them to anyone.