New flats in ockendon

I was called to a property in south Ockendon where the door would not lock,I arrived to find the centre case was at fault, I returned with a new centre case but I could not remove the mechanism without forcing it out which may of bent the mechanism. I informed the customer and advised that it would be better to replace the whole mechanism he agreed to this. I returned with tbe new mechanism and tried to remove the old mechanism after some time it came out when I looked who ever fitted the lock had screwed through the back of the case in to tbe door which was why it would not come out. I fitted the new mechanism and the customer said it was better than when he moved in when the flats were Brand new.