So I started looking into the Employment Rights Act 1996. Rumour has it that, should you want your wages this month and don't receive all of them, you may need to prove financial hardship, else you'll get what's owed next month.
Of course, not all of the act applies to the Armed Forces. In particular, Section II - which deals with deductions from wages, does not apply. However, Section I does, and that includes the right to an itemised pay statement before or when wages are received. I've still not got one - and my pay is off by about £600. Anyone got a link to the full text of the AFA 1955?
