My cousin is being disciplined in work - was he at fault?

Warning, long post.

Bit of a background story, he is 19, his mother is Irish and his dad is German (my mam's sister married a German). He grew up in Germany and he is now 18 and arrived in Ireland recently. He wants to spend a year working here and mix with his side of the Irish family.

He is working now for a certain Irish store. He was assigned a task of 'stock checking' which occurs during normal store opening times, although you may voluntarily begin slightly before opening times or finish slightly after store closing, depending on what suits you, as long as you put in nine hours a day over two days. They are not paid extra or given travel expenses, as it says in the contract that you have to commit to working with the sister branch no more than five days a year.

Alongside him, another girl was assigned stocktaking duty, the sister store that they were deployed to is relatively far from the one where they're based normally in terms of public transport (the girl doesn't drive), so he was asked if he'd bring her.

He made it clear that he'd see her at the car park at 07.00 in the morning and make their way to the other store, at work for nine hours after they arrive, then drive back, thus hopefully beating most of the traffic. (She lives in the town of the base store, only walking distance away, he lives a 10-15 minute drive way.

He arrived at the car park a few minutes before 07.00 in the morning and waited for her, 07.15, 07.30, 07.45 .. still nothing, he tried calling her several times but it just kept ringing out and after the fourth or so attempt just went straight to voicemail. At roughly 08.30, she sauntered in and grunted something that resembled 'hey', and she put in her earphones and didn't speak for the journey, no apologies for being late. (Frankly, I think he was mad to wait that long).

Upon arrival, he said that it wasn't cool being late, and that if she wanted to get a lift the next day, she'd have to be on time, as my cousin had arrangements after work that he had committed to and counted on arriving at roughly 07.30 and finishing at 16.30.

He arrived the next day at the car park of the base store and no sign of her at 07.00, so he waited until 07.10, started the car, put it in gear and drove off. Only for her to arrive at 08.10, with no lift.

The next day when he was back at the base store, he was called to the managers office and lambasted for what he had done. He was told that he was going to have a disciplinary meeting later that day with the assistant manager as a witness.

He prepared for this, and brought his phone into the meeting and secretly recorded the meeting. The manager said he committed 'gross misconduct' and that the sister branch was one person down because of his selfishness. She said that in Ireland "7 O'Clock is only roughly and he should have made himself clear and not committed to anything after work" and the he should go to Switzerland to satisfy his 'clock fetish'.

The problem he has is that he recorded the interview without permission or knowledge from the manager or deputy manager and he didn't have a coworker as a witness, nor was he offered an impartial witness as he wasn't made aware of the right to a witness of his choice.

Can he use this recording against the company?