Door Locks breaking
 

2001 model has been excellent since buying it but in the last 6 months I have had problems with both front door locks. First the drivers side intermittently would not unlock. At the next service they seemed to fix it. Now the passenger side has done the same. Dealer tells me that the on board computer says both locks are reporting faults and need replacing. Soft reset allows the fob to lock and unlock the doors but he says the dead locks are not being deployed.......
1. What does that mean?
2. Is there a known fault or am I just very unlucky?
3. He quotes £400 parts and labour, is that excessive?

best regards
Dearthy