MrD refusal to investigate allergans in food when order requested no onions

I ordered from Mexi go go in Sandton and requested no onions as I'm allergic, I received my food with onions, after picking for 15 min I decided to just throw it away as I did not have my epipen hand, now MrD is refusing to investigate why the restaurant did not read comments on the system of no onions as I did not take pictures of the food I do not want a refund or replacement meal I just want an investigation on what what happened, and an apology from the restaurant not MrD, it seems to me now that may it could of actually been a problem with their system, seeing that they just can't take my order number call the restaurant and ask why did you add onions