Got detention for using public bus stop

Our school banned us from using nearby bus stops (not the bus stops right outside the queue) because of "safeguarding". My friend and I went to the chicken shop nearby and got the bus from a stop later back (opposite the chicken shop than the prohibited ones near the school. Little did I know the deputy head was waiting at the banned stop. My friend and I received a 1hr detention for this. Is this common at other schools? Anything I can do to get the detention revoked?

INFO: the deputy head and head of year don't know that we went chicken shop. should I tell them?