some of their staff have revealed their tactics. Basically they look over your car and emphasise any negative points and gain their bonuses by how little they can offer you.
I know a few people who have used them and they always knock you down from the initial quote for faults they say you did not make clear. Where are they? Around the back of Stansted Airport ... there's a wide variety of car crushers and v cheap car sales places in the same area
Don't use these guys unless you are desperate.
The price they quote is low then the 'engineer' comes to look at the car and will bring the price down on every little thing they can.
Far better to advertise in the local paper, or on Ebay.