Citizens of the UK at present get a master class demonstrating how a potential referendum can be abused and become a political football. One party 'promises' to hold a referendum about the country's future relationship with the EU if it gets re-elected in the next general election due in 2015. The other party claims that it will hold the same referendum - but only if the EU wants to take more powers away from the British government. In both cases these promises are not worth the paper they are written on. There is no legal requirement for any party - in the UK or any other 'mature' democracy - to fulfil election promises.
In any case the referendum is merely being used under duress and
used as just another trick to gain the unadulterated power that each
party machine craves.
If politicians honestly want to return power to the citizens (or as
they always claim: 'Listen to the People') they would regularly
consult the referendum and introduce it as binding requirement when
any significant political decision is made.