Big Easy complaint: Unjust Treatment of staff

My son was taken on by Big Easy via a friend and had worked a few months with no problems until the woman doing the rota (Toni) decided to rota him on his college days! She was told what days he could and couldn’t work at the interview. He called and texted Toni to let her know that he was at college and she did not reply over 3 days!
He managed to change one of his shifts with a friend (Harry) who agreed via the app but didn’t show up. Toni sent Lewis a text to say that he had been sacked! And she knew about the swap…how is that fair? Harry still has a job!
When I called to ask why my son had been sacked through no fault of his own, she said he had also dropped 2 drinks near a customer! He dropped 1 and apologised, and the waiter cleaned it up…..it’s a restaurant these things happen; is that any reason to sack an 18 year old in his first job and to lie about what happened? Harsh, favouritism and unfair comes to mind!
A place NOT to encourage young people to work