Employer went to london without paying me... what can i do?

i worked for a friend of a friend for 2 weeks. at first i was just helping out but for the second week they offered me a job for a few hours every other night. i started getting messages saying not to come in today ect but then when payday came and went i went round to their apartment. they said they would come down to me but they never did. they have been avoiding me for 2 months and have moved to london to start the business there as it failed in leeds. they owe me �85 at LEAST (minimum wage of the hours i officially 'worked') but they said via a friend that they would give me �30 so i settled on �60 but haven't heard from them since. what can i do or do i have no rights considering they where 'friends' and i don't think they put me on their 'books'. im 18 and this is my first proper job from college and i don't know what my rights are and im a little stressed out. help?!