Pensioner says clamping of his car in hospital parking area is not legal

I am an elderly man. I brought my chronically ill, invalided wife for a physical check-up before 9am. She was discharged four hours later. When I went to the parking lot, I was shocked that our car had been clamped. According to a witness, this was done five minutes earlier.
As on former occasions, I photographed — in good faith — the disc issued to my wife by the Irish Wheelchair Association, which would expire on October 1, 2015. The renewed disc has since arrived. Despite using copies down the years, and parking in several venues, including the hospital in question, no one was callous or greedy enough to clamp my car.