6 McNuggets for the price of 10

I ordered 10 piece McNuggets and received 6. When I tried to contact customer service they didn't exist anymore. After I lodged the complaint on the McDonalds app I received a notification to say that the order was cancelled so they obviously just removed the evidence of their mistake instead of fixing it. McDonald's as a company has hardly been good, but now they fully aweful on almost every possible criteria.