Just make sure there are no birds still nesting before you cut it down.

If you are having problems trimming it then why not cut it down to a much more manageable height (3-4 ft) and trim the thickness as well. It may look rough for a few weeks but it will soon green up again. I cut mine down to about 9" last year - seemed to be nothing left but bare wood. It's now about 3ft high and green (it's still destined to be removed as soon as I can get a blacksmith to give me a quote for iron railings)

I've looked at that option Snoop but the lengths I need don't fit either imperial or metric measurements and the cost of getting them cut to size and re-welded with fixings would be almost as much as getting made new - and I would still need a blacksmith to do the cutting and welding.