S. Chand Publishing — my wrong order and payment unsuccessful

Sir, i've ordered the book of modern physics by mr. R. Murugeshan and kiruthiga sivaprasath., there were two books with different cost. I have chosen the book with another paperback sir., so i wants 4th o cancel the order & replace the order with my correct reference book.

Another complaint is about my payment sir. Total cost including delivery charge is rs.401 for me sir., i paid already, the amount have been debited. But the order receipt shows payment unsuccessful & pending. Now how to cancel the order sir?