My boyfriend and I parked today in his taxi using my blue badge, we returned after 30 mins to a parking ticket stating we have gone over the allocated amount of time allowed, we were only gone 30 mins. There is a sign saying disabled are not exempt from parking on yellow lines, which although was close to the car, i didn't see it before parking, they want £60 within 7 days or it goes up to £100, where do I stand please. thanks