Calm down, people! It's actually quite logical to assume that
A. Fire-spirits would all work for the same Vala.
and
B. That Vala would be associated with fire in some way (Aulë the Smith, Varda the Star-Kindler).
Just seems to be wrong, that's all.
I don't think Tolkien ever said the Balrogs followed any particular Vala (apart from Melkor).