Want To Remove Product Quantity If Order Fails

Hi Geeks ,

I am running opencart 1.5.6 and if someone orders Products and go back without payment Order Gets Failed But Quantity Remains There in Failed Product , I just want if some one orders and order gets failed , The Product Quantity Should Not Be There Just Other Information , Because If i am having 1 Quantity in Some Product and It Goes Out of Stock When Some One Fails Order

Hope Members Will Help Soon