Instant dismissal......again.........n… info plz?

I worked in denmark for my english based company for 4 weeks..the last night the danish contractor paid my hotel bill of £100 as a tankyou...back home..i had forgot to get that reciept,so i wrote on a bit of paper exactly that and claimed £60..my bosses investigate..confirmed by Denmark bloke that it was gratitude for a great job done...and after 9 months with no prev complaints...i was an instant dismissal for gross misconduct! i also spent bout £50 on farewell drinks with the site lads too.;Have i got a case?I did not tell the boss that this was paid by the Denmark bloke initially...not untill the 1st discipline hearing.But it was a confirmed gratuity payment that went t£ts up.What you lot think.?