Q: vodafone locked iphone4s

How do i get vodafone unlocked from my phone?.. I have taken phone to AT&T.had sim installed and was told verizion had lock on phone...took it to verizion., they unlocked it...several days late took it to applestore and was told vadofone has it locked..restored and undated phone thru itunes. ..get message "sim not vaild" when card in inserted...please help can't access steps to unlock per vodafone website..please help?