CRAZY WORLD WE LIVE IN !.
Well you pleaded guity, and you did have drugs on you, so first of all accept it.
Life is a lesson, we all make mistakes.
Not much point appealing as a conviction is a conviction, its on your record until you die.
Sounds like your record company are complete morons, as all the senior management there are proberly sniffing the White stuff every weekend themselves.
Pick yourself up, grow some balls and start making some changes to your life, if your band is that good, then look for other companies, if not, let your other members have their fame, and live your own life.
The convicted rapist Mike Tyson is allowed to enter this country and tour giving talks on his life...As I said : What a crazy world we live in mate.
BE BRAVE & BE LUCKY