ABSOLUTELY Unhelpful and rude

I ordered a meal via the Mr Delivery App (which doesn't give you an option to add or remove ingredients). Immediately after placing my order, I called the restaurant to request the removal of onions (because I am one of the lucky adults to be allergic to them!)

Note, this phone call was made SECONDS after the order was placed, I was told by the staff and the manager that my order has already been made!????

They made my meal in a few seconds???

Furthermore, the manager's unhelpful attitude makes me wonder if he is suited to be a manager at all. His responses we along the lines off, "Well none of our other customers have issues," and ,"The chef already made it, it only takes two minutes. Nothing can be done"

At no point was I offered ANY apology, help or any way around my issue.

I find it difficult to believe firstly, that a meal can be prepared in two minutes, and secondly, that a person in a managerial position can be so rude and unhelpful.

Frustrated and searching for an allergy tablet!