WE ARE VISITNG CHINA FOR CANTONFAIR WE WANT TO GO HONGKONG AND BACK TO CHINA. VISA CHARGES

WE ARE VISITNG CHINA FOR CANTONFAIR WE WANT TO GO HONGKONG AND BACK TO CHINA. WE GOT SINGLE ENTRY VISA , HOW TO VISIT HONG KONG AND BACK WILL IT BE POSSIBLE TO GET VISA AS WE HAVE RETURN TICKET FROM GUNAGZHOU ONLY PLEASE ADVICE HOW MUCH CHARGES , AND HOW MANY DAY S
WILL IT TAKE.