Hi
I see your post was back in 2009, but thought I would reply anyway
I had L5-S1 spinal fusion done, 10 years after suffering after falling from a horse at 15yrs old.
I too am from NZ. The first specialist I saw was in New Plymouth, told me to do exercises. 18 months later, I was still suffering (age 23).
We moved to Auckland in 2001, and seen another specialist as I collapsed and couldnt walk properly. MRI was done, dead disk. He was going to put a clamp at the bottom and top of spine with a rod between, and hope it fused. Drawback was I would have to go back under the knife to get rod removed.
Got second opinion, seen a Dr at Ascot. Age 24 by this time... He wasn't going to do it because of my young age, but he researched his patients and decided he would do it. He scraped out the dead part of the disk, put in a "spacer" (which resembles a holey thumb/finger thimble), took a bone graft from my hip, stuffed that in there, and put in 2x screws. I don't ever have to go back and have it out. Surgery done in 2002. Up out of bed the next day, 1 week in hospital, 6-8 weeks recommended off work (I returned at 7 with dr permission).
Today (March 2013), I can walk, run, play etc. Although, I do need to keep up the lumbar exercises for the muscles. Know when I have overdone it in the garden as muscles ache.
I know its been 4+ years since your post, but I hope you have it sorted by now, instead of Dr's fobbing you off cos they don't want to treat it, or don't know whats wrong. I would strongly recommend a 2nd & 3rd opinion before going under the knife.