How can I fix my Hitachi C28WF560N?

My tv was repaired a couple of weeks ago because it had the 'hourglass' screen problem. That was fixed fine but now the picture seems to be too big for the screen!! (Text is missing from the bottom of the screen). Phoned up the tv repair place and they said that is a simple case of just using the remote to correct it but would not tell me how to do this over the phone. Could anybody tell me how to correct this problem. Many Thanks.