Ok I have fixed it, I had to drill out the hole with a 5.5mm metal drill bit. I then used an 8mm tap to rethread the hole with a 1.25mm thread. I had to cut a 17mm hi-tensile steel bolt (8mm) to 10mm. That fixed the problem of having a thread stuck in there.
I then had to waste 4 drill bits and drill through the hardened steel washer that Ford use, so i could fit the 8mm bolt through it.
I then had to find where the clamp in the release mechanism was slipping and rotate the cog off the seat untill it meshed correctly. Upon doing that I bent the spring that holds the release mechanism against the cog to provide more tension.
I then lined it all up and re assembled the seat height lever, tightened it up to buggery and gave the seat a few hard kicks to see if it slipped.
Problem solved, thanks for reading this post. (not that anyone cared :( ...)