Employment Law Trainee Chef

[imd123]

My son is 18 and has completed 2 years at catering college. Last Xmas while still at college he got a part time job at a local restaurant. He was paid �4.25 per hour which was fine. When he finished college they offered him full time work and kept paying him �4.25 per hour. Some weeks he worked up to 55 hours inc weekends but never got time and a half or double time. They have since put him on a flat rate of �138.68 per week and he now works up to 60 hours a week sometimes over 7 days for this. He has no contact of employment. Can anyone explain how his pay may be worked out please? It may be hard for him to approach his employer and I would be very grateful for any help from anyone out there. I have also posted this question under 'law' as I was unsure where to post. Many thanks to anyone who replies.