I've recently purchased a Ford Transit custom, and has a company install a set of two seats from a mini-bus ( also ford ) behind the front seats - the seats are supposed to be new as they have been removed from a mini-bus as part of a disabled conversion.

The seats look fine ( and new ), but when I sit in them and do the belt up - if I pull hard on the strap than runs from the shoulder to the hip the belt just flows - in the front seat if I do that the belt it sort of locks - but these don't - don't know whether the locking thing is only for front seats because there is more damage to do there, and for rear seats it just sort of keeps you in place.

Any advice gratefully accepted.