Another problem with PAYD is that you can only access the core menu at specific times. During a week long visit to Leuchars some 3 years ago my colleagues and I could only make the core breakfast, all others were out of core hours. At the end of the week we were all some £60-70 out of pocket.
It was what people asked for, and for some it has worked well, but it has taken a huge bite out of the culture of the military that is detrimental in every respect.
Loved the life whilst I was in but glad to be out of it now.