Where can I get my old iPod 4g click wheel fixed?

Where can I get my old iPod 4g click wheel fixed?
My very old iPod no longer powers up at all when plugged in to a socket or computer or a dock. I suspect the batteries have died. Also the click wheel no longer 'Clicks'. Only one side of the wheel clicks and so (when it was working) sets of random commands. Is there a place in London,UK where I can get this fixed without losing all my hrs and hrs of music that I painstakingly put on there in REAL TIME in 2005???

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