Farm is almost always the answer
farm
it was just about 29min. you should have 290 CS. you had 175.
CS is valued significantly more than kills on vayne.
Ive had games where i went 10/0/2 with like 100 cs at 25. and got an A+. but went like 1/3/4 with 240 CS at 25min and gotten an S-
11 Wards in 28 mins. should try to bump it up to at least .5 Wards/Min if not up to .8-1.0 WPM 6.1 CS/Min, should try to bump it up to 8 CS/Min for S+
KDA stops mattering after a certain point (I think it's 7.5)
And how was my last thresh game an S+. Mysteries of rito