mother and autistic son face deportation to philippines when their visa expires today .
maria sevilla and her son tyrone have lived in australia since 2007 but have been told they need to leave due to tyrone 's autism .
tyrone has designed a poster asking the immigration minister if he could stay in the country and hand-delivered it to the minister 's office .
the family live in queensland where maria sevilla is a nurse at townsville hospital .