Well I’m certainly sorry for the confusion.
I know that I personally have eaten several big heroes before; one I intended to, and one I didn’t…I eat ten heroes at a time and I clicked fast without paying attention.
(I’m not saying you did this, only that it is possible.)
Support is the final word. If you ask, they may be able to furnish proof to you of these missing heroes.
P.S. In answer to your original question, yes, you should receive two heroes, if that’s what the Brawler pack says (I don’t have that deal to check). Just so you know, 300 gems is roughly the equivalent of one 3* hero (higher* if you are lucky), or two 1-2* hero’s (two 3* if you are damn lucky!)