As they say, there are always 2 sides to a story... what if the vet has to hire a babysitter for calls, or has a parent ill. What if the client has been mean or rude at some point. What if none of the 3 close vets is familiar with minis or breeding. My mom deals with a LOT of crap to be a vet and I have heard her be cussed out because she couldn't get to a horse because she was already busy...or have a client demand all their records, refuse to pay their bill and then be mad 6 months later because she wasn't "there" for the colic, etc.
You also have patient continuity to deal with... Yeah I gave all my shots, you dont know what your talking about, my horse can't have confirmed encephalitis/rhino/ flu/ rabies/strangles/etc! That vets license and family life are on the line every call she makes.
Not saying you have been that way to this vet but what does she deal with on a regular basis to cause her to change policy??
A friendly phone call and what can I do to help/fix it may solve your problem or at least let you know what the problem(s) is(are)!