If the garage has had it running once, it doesn't sound as though they need re-synching. If they had the correct diagnostics, it should have shown up there. It sounds to be more an intermittent connection somewhere. If the starter relay is clicking in the fuse box (does it click once when you turn the key to the start position and then again when you release the key?), you should have power going to the starter motor solenoid from that relay. If you have, you have a duff starter. If not, a problem in the fuse box (the same fuse (MF2) feeds both the relay coild and the starter solenoid).
A duff crank sensor wouldn't stop the engine turning over.
You'd be advised to download Rave (see threads on here) or buy one of the CD's off fleabay for about three quid which has all the info you need.
Good luck.

I'll give a positive answer.

Replace the under bonnet fuse box. If still no better then the becm need's looking at.

You must have the right people working on your car else you'll be throwing money away.

i would try starter to bat and see if it turns over, i dont think it out of sync, as garage would not have got it started..

I know it's been mentioned before but..... as regards the transmission inhibit i.e. P or N could the selector have come adrift a little and just not be catching? Try keeping the key turned while working the lever through from P to 3 and back again. If it gives a kick part way through then that's it.

Cover the brake though just in case it starts quickly and you are just about to select R as you move the lever!!

theyve had a diagnostic on it and its says everything is fine, your mentioning the gears, we had to push it into the garage, so they obviously had to push it to move, that wouldnt have anything to do with it would it??

im hoping they checked the starter, thats kinda basic thing to check id think when a car aint starting. i did tell em there was no volts going from the battery to the starter when i turn the ignition.

the fuse box clicks once when you turn the key but does nothing when you let go.

i remember trying it in high and low, but the gearbox wouldnt even change over when i did move it, you know how usually you can hear it clicking over, theres nothing.