Incorrect Order

I order regularly from the Mr D Food app and never really encountered any issues up until 2 weeks ago. I placed an order for a double quarter pounder with cheese meal from MacDonalds only to receive a single quarter pounder with cheese. I've emailed Mr D to notify them of this error in which I had received a prompt response from not 1 but 2 client services agents letting me know that my query is being dealt with. Well clearly it hasn't been resolved as yet even after 3 more emails to the ladies who initially responded to which I have now received 0 response to. What turned out to "be" a "sweet" relationship has quickly turned sour. UNACCEPTABLE