Read items line by line.
Correcting an error here is much easier that organising a refund or an extra payment
Have you selected each item you require?
Are the quantities correct?
Have you selected items you do not require?
To correct your selections:
Use the red X to delete a complete unwanted line item.
You can adjust quantities by hovering over the Quantity box and using the up/down arrows.
You must confirm changes by clicking Update Cart.
When you are happy, click Proceed to checkout