Ordered a burger SPECIFICALLY with a gluten free b...

Ordered a burger SPECIFICALLY with a gluten free bun (paid $2 extra for it) and no cheese. The burger I received had cheese and a standard bun. When I talked to the manager, they were quite rude and only agreed to replace the burger itself and I had to pay an additional $2 for the gluten-free bun I had originally paid for. So I ended up paying for TWO gluten-free buns but only received the one. The first burger I had to throw away because I m allergic to gluten and dairy (casein).