St Albans Driving Test Centre - Difficult Instructors

I don't know if they do this intentionally, for you to not pass in St Albans, UK. This is the 3rd time i am taking my test and out of this 3, I personally believed in the 3rd one, even after the instructor took me to very complex roundabouts, it was almost like he wanted me to fail at some points, but I still scaled through all of them!
So, what could he fault me this time as a serious fault - he said i parked a little away from the kerb and 3 cars from the one in front! How is no one assessing what the instructors are doing because there is no point taking these situations as a case filing if nothing is going to be done about it.

Plus I pay close to £400 everytime to get an appointment date plus use my instructor's car for the practise test which is a bloody rip off! To practise per hour, it is £40 and he is saying he wants to increase it to £45 from next month. I don't have anyone around me to practise with their car unfortunately. So I am stuck with renting an instructor's car . Can anyone share anything helpful please?