Assuming he is looking in the right place on the EPG, channels 169, 170 on an Irish card, I suspect his best move is to power the box down for a couple minutes and then restart. If that didn't help there are reasons why BBC in particular wouldn't work, a couple years ago BBC went FTA and did something along the lines of moving their transmissions to a different satellite to the most of the other channels (one reason was a half-hearted effort to to reduce the signal coverage to the UK region). So perhaps an dish alignment problem could affect BBC channels and leave most of the others running. There's a Sky FAQ here [broken link removed] Q27 covers some problems with the LNB that affect BBC. He probably needs to call somebody out to have a look at his setup.
If he wants to try something else while he's waiting maybe follow the steps in Q28 in the FAQ and force a system upgrade, less drastically he could take the card out, turn it upside down and reinsert it. BBC1 and BBC2 should now be on channels 101 and 102 and a whole bunch of regional variations on somewhere between 800 and 999.