It happening to have a PSA who even you are giving the best support rate you lower.Maybe you are below his/her expectation what Sponsor needs to show to them.I wouldn't bother with that too much and would just proceed the way I am working.There is always a last option to reassign them if you get to the point that could be better for both sides.This is a team work and we don`t need to accept so hard someones evaluation in direction to successful results.