People unclear on the question: me.
You say that "the QR wheel spindle snapped". I assume you mean the rod that runs through the hollow axle and has a cam on one end and a nut on the other? "The shop replaced it with a solid one".. The QR spindle (rod) again?
But those aren't axles. So "breaking rear axles" and "snapped axles" makes no sense.
Where are whatever-they-are breaking?
Beyond that, I'll refrain from more output until I get input with the correct terminology.
Ditto. Visit the park tool site, they have an excellent glossary on bike components. I am not sure what is breaking either.
Or post a couple of good pics of the broken parts.