The Driver and Vehicle Standards Agency (DVSA) has implemented strict changes to driving test bookings to stop bots and third-party scammers from reselling test slots. You are only allowed to make 2 changes to your booking, you can only move your test to one of the 3 nearest test centres, and it is now against the law for anyone other than you (the learner) to book or manage your test. [1, 2, 3, 4]
