driving home last night luckily only few hundred yards from home there was an almighty bang from the nearside of the car and a rattle & grinding noise knocked it out of gear & rolled downhill to home, on looking underneath oil was pouring out quickly put a bowl under to catch oil, on examination the diff casing is totally shattered what caused this I have no idea but a replacement gearbox is needed, the code for box is JCV is this the only box that will fit my car? or will other codes from same year fit,

this is third Octavia I have owned & first ever problem, mileage on this car is 108000 my two previous octavias  had covered over 160000 when I sold them

You have my sympathy, I had the same thing happen on my Octavia Mk1 when it had 98k on the clock.

I know a good few years ago mk3 and mk4 golf gearboxes were popping diffs quite often, turns out the rivets used in the factory were the wrong type leading to fatigue and then failing, meaning the diff fell to pieces wrecking the gearbox with it.