I never experienced PAYD while I was in, but at a recent re-union was told a story of a young squaddy who was pretty poor at organising his personal finances, being warned for going abroad for a 6-month long detachment, being paid an advance of his allowances prior to departing, only to have his bank take the lot to recover his overdraft; end result was the serviceman was unable to deploy anywhere, but now had an advance to pay back with no money in the bank - bizarre.
I wonder if the bank had re-assessed the risk associated with lending money to servicemen and decided to cut their potential losses?