Really good driving instructor, North London area (N6)??

I'm a fresher, failed first two tests (one before uni, one over xmas), and I have one booked in nine days' time. I consider myself to be a decent driver, very annoyed that I didn't pass first time and slightly confused as to why I didn't pass second time. Basically I'm looking for someone to take the test with, take a few intensive warm-up lessons and iron out any faults that my previous instructor didn't. (I got on that ok with my previous one but I don't think he's a very good instructor.)

Any recommendations for a good instructor in the N6 area? Or, indeed, any tips?

Thanks in advance xo

EDIT: Hendon test btw

http://samisdrivingschool.co.uk/

I think this is my instructor, didn't realise he had a website now.
From my understanding he's got a lot of students like when I had him and I had to make sure I booked in advance for appointment. If he's late, he'll make it up and sometimes even gave me extra time.

I used him on recommendation from my uncle who was taught by him as well, he's pretty chill guy.
I did Hendon test centre as well, if you already know how to drive, etc he'll get you go down to hendon and essentially drive around there and to practice tests from the centre.