Not sure exactly what you guys have seen or havent, but there's a one hour halloween special that went out between the first and second series. It's up on youtube, all the parts seem to be there and the quality seems decent. The same person seems to have uploaded alot of the episodes from both series as well, but i havent gone through 'em to check if everything is there and as it should be.
They had all the episodes on the bbc website too, but they've all been pulled. There's still a ton of cool videos and teasers/ trailers but no actual episodes.