Can someone please explain to me how, with all of the fillers Mary's had injected into her face, it now looks like her face is quite literally sliding down and off her head? Is it a result of her not keeping up with the fillers? I'm 2 years younger than her, have never had work done on my face (and never will - too afraid of needles and possible side effects), and am regularly mistaken for being a decade younger than I am. I literally can't wrap my head around how she can look so awful in spite of the vast resources she has access to.

I'm no expert but I think someone like Mary will only listen to professional advice to a certain extent. Ultimately she thinks that her way is the best way and to hell with anyone who says differently, even if they are the best that money can buy. I think her current appearance, for example her her seeming to slide off her face, is not due to the actions of her cosmetic surgeons, but rather Mary's demands of them.
My granny retained a youthful face well into her 80s. She only washed her face with soap and water and never wore make up. Her approach of "less is more" seemed to work well, and with Mary it shows how going all out can lead to ructions in the long term.