iphone 5 bluetooth merceds c300 not pairing

i had an iphone 4s on a 2009 c300 mercedes benz, worked fine change to an iphone 5 and worked for a couple of days , deleted the old iphone reset the command and still not being able to pair, i used to use the 1234 as passcode on mbz and worked not any more any help will be greatly aprecciated.