Save game restored!!
I just thought I would share with everyone on here a fix for what happened to me(starting episode 4 and my save game getting overwritten, forcing me right back to the beginning of episode 1)
Contrary to what is being said by the 'experts' your save game isn't lost!
I'm just repeating what someone else posted on here so I won't be taking any credit.
Here goes: copy your save from slot 1 to slot 3(copy NOT delete!)Then start playing your game using slot 1. Choose episode 4 and magically you should find it picks up where you left off with all your choices in tack.
Obviously if you already have all your save slots full then this might mean you lose what was in your third slot, however it will at least give you what you had in save slot 1 back.
I have no idea why this works but it does. I can only assume its related to the issue of save slot 3 being corrupted somehow.
I have now FINALLY got to play episode 4, thanks to the guy who originally posted this fix! I hope this works for all.