DDs both had these for tea last night. DD was munching away quite happily when she stopped and said "Am I supposed to eat this bit?". It was a lump of cardboard covered in batter!! .
I have just phoned up the Birds Eye complaints line and they apologised sincerely and explained how it could have happened. They have told me that they will send me a package with an envelope in for me to return the piece. They are going to send me a £10 voucher for compensation too.