If you transfer too much money we will email you a store credit code for the difference to use on your next order.
If you transfer too little then we will contact you via email to notify you. We can then send you a paypal invoice for the difference. You do not need a paypal account to pay the invoice as it can be settled by card.
Alternatively we can amend your order so that the amount we have received covers the cost and send you a store credit code for the difference.
Unfortunately we do not currently have the facility to process refunds via bank transfer so recommend paying for your order by either paypal, debit/credit card or realex. This will also avoid your payment being subject to any fees from your bank.