McDonalds Mayo Instead of Tartar Sauce

My husband and I went to McDonalds in Bayside Mall. We always order a Fillet of Fish Meal. When the food arrived we saw that the Filled of Fish burger had mayonnaise instead of tartar sauce, as the menu states. On bringing this to a staff member's attention, she said she did not know what tartar sauce was? Never going there again. Few weeks later, we visited McDonalds in Parklands. Guess what? Mayo instead of tartar sauce. Well I guess it's a lot cheaper to use mayo? Goodbye McDonalds.