Clouseau said:
Lets face it; this happened all the time when there was some chimp-writer looking after your pay account.
In my experience, any faults in the past were caused more by some chimp dabber going on three weeks' leave/course/exped, not telling the UPO/Ship's Office, and then coming in to complain three months later when he could be finally bothered to look at this pay statement and realised he'd been charged food and accom throughout. Not that chimp Writers have never been at fault, but the fault has almost always lain squarely at the feet of the dipstick Dabber/Stoker/WEM/whatever who assumed that Writers' balls were made from crystal rather than flesh. My other personal favourite is the moron who thinks he's entitled to something "because my Chief said so". Said Chief is never, it should be noted, a Chief Writer, so draw your own conclusions as to the competency of someone taking pay advice from a Chief Phot and the case peters out right about there.
However, your point still stands in one respect. Since JPA is a self-service system, the potential for cockup on behalf of the great unwashed masses who have either not bothered doing their JPA training, not able to do their JPA training or too thick to understand their JPA training, is correspondingly massive. Only this time they won't be able to blame it on the Writers, although I'm sure it won't stop them from trying. This is no fault of JPA, it's the fault of the self-service chimps who aren't taking the implications seriously.
JPA is a massive change, and it affects YOU more than it affects any Writer. Start taking it seriously and get that training done wherever it's available. But I'd also advise anyone in receipt of any kind of specialist pay/between drafts/moving home/changing bank accounts to start putting money aside. There are some problems you can't blame on chimps of any persuasion and it would be wise to be prepared.