stop start error

Hi everyone I'm having some sort of electrical gremlins with my Leon. It's booked in for work soon so im hoping this might solve the issue but until then i've been trying my best to either diagnose the issue myself or fix it with my limited skills and resources. Apologies this is a long thread...

I have 2014 Leon 2.0 Tdi 150 with 46000 miles and in recent months it started to show signs of minor hesitation when driving in 3rd or 4th gear in revs between 1500 to 2000. The issue got progressively worse to the point where the car started to jerk and hesitate severely and I could only...