Problems with the conduct of a test can often be sorted out without going though the pain of a full Reg 6 process. Talk with your CFI and/or Head of Training. If they think there has been a problem then they can talk to the CAA's senior Flight Ops Training Inspector who will speak with the examiner involved. If there is any doubt about the conduct of the test then you'll be offered a free retest. Only if the examiner involved is adamant that the test was properly conducted will you need to go through a Reg 6 process which will take some months months. Full Reg 6 appeals regarding flight test results are very, very rare.