Well you did not say where you are located but around me, here in North-East Iowa, that size of order would not be problem getting filled.
The only thing I can think of is the fact your statement: "I farm some white timber soil and muck and the racehorse numbers they want me to buy just never work on my soils." Might cause some of the salesman to think you just want real cheap seed corn. Don't have any other idea for the bad service.
Here locally I get pestered to death by guys trying to sell me seed. I do know you are starting out way late to real have a good choice of seed this year. I had all of mine ordered by Sept 1 this year. Even then some of the numbers I wanted where already sold out. Seed supplies are going to be short this year so your choices will be more limited than normal.