naz shah claimed to have been forced into abusive marriage aged 15 .
but mr galloway says he has marriage certificate showing she was 16 .
accused her of playing into stereotypes and demonizing pakistanis .
labour hit back , saying there are two marriage certificates , and they have the original from 1988 showing ms shah was in fact 15 .
party say they wrote to election watchdog over mr galloway 's allegation .