eCart5 added coupon to confirm.phpt, submit coupon button clears billing address etc.
Added PromoCode text and button to confirm.php as directed by the Webassist pdf.
That element works but when the 'submit' code button is pressed it clears the billing and shipping addresses on that page.
This is eCart5 - www.belindaclark.co.uk - go to shop and follow usual checkout trail.
Also added php etc. to help