Let me know if you resolve the situation..... I took my brand new Nissan Micra back to the dealer because of a problem which sounds the same - funny crunching sensation and no braking..... and they told me that there was nothing wrong with it and made me feel like a fool. I had a few hairy issues and sold her last year. I got another Nissan Micra (I can park them - this means I like them) - and unfortunately I have the same blooming problem - and no one can tell me what it is or do anything about it.....
