Hi, basically I had the same issue...and it was stuck in very very tight! I literary had to use full force to yank it out....if you have a facelift S3 you'll see two pressure clips at the top that move when you pull Don't be afraid to give it a good yank! BUT make sure you are holding it from a solid part (not the flexible edges that could damage the screen)
I bought a replacement unit 6 months ago and keep putting off changing them. This isn't inspiring me with confidence that it'll be a straight forward job lol
It's very easy to do! takes about 5 mins to get it out....I'm planning on taking mine out this weekend to tidy some wiring, will try and post a video/guide