I am so sorry that you have had to go through this! It seems like such a horrible thing to go through, this vet is making a bad situation even worse then it had to be!
I can't believe the vet hasn't called back and that he hid when you visited! I've just got to give you a virtual hug!
I don't know if this will work, but you could schedule ANOTHER visit, this time EXPLICITLY schedule it with THAT VET! Like a meeting with the vet, then he couldn't get out of it, unless he canceled.
Otherwise, if you send the letter, make sure to send it DELIVERY CONFIRMATION!!! That way they can't get away with saying they never got it!
I'm hoping he steps up and acts like a responsible person. I'll think good thoughts for you!!!
-Vicky