exactly, I can see them not going to depth about how the chicken is bred and I can understand the hatchery not even knowing the whole heritage of the breed but the should certainly be able to tell you which strain they handle.
I would try again and tell them you aren't interested in knowing what the cross is to make them that you just want to know what variety or strain of CX they are, cobb, Ross etc. They shouldn't have a problem telling you that and I guarantee they know which one they sell. As a side note Murray...