Drivers Side Door Lock

I'm having a problemwith my volkswagen 1.4 99 golf new model. The lock won't work on the drivers side. The central locking works on the button off the keyring but when I try to open with the key the doors won't open. I've an idea it might be the central locking motor? Has anyone had a similar problem with their Golf? How much did it cost to get fixed?

Hi sounds like the excentrick has broken not a big job and the parts should cost about £10 from a deler , but its a bit fiddaly to assembel