ford focas (51) diesel?

First of all I would give the locks a good squirt of wd40 , put your key just into the lock but dont push it all the way so you can get the wd40 in , you mentioned your keys are new , sometimes you have to reset central locking it should tell you how to do this in a haynes manual . If you dont have one try sitting in the car close the doors and lock the doors using the keyfob ..hope this helps

Kev
December 2008