Use JS to change + to - in your WP accordions.

WPPlusMinusAccordion.js

$('.panel-heading').click(function(){

	$('#ew-accordian').find('a').each(function(){
		$(this).attr('data-before','+');;
	});

	if( $(this).find('a').attr('aria-expanded') == 'true' ) {
		$(this).find('a').attr('data-before','+');
	} else {
		$(this).find('a').attr('data-before','-');
	}

});