If you've paid for your order by cash, you'll receive a Return Voucher worth the full value of your return. These are single-use vouchers valid for 6 months from the date of issue, and you can use yours to shop on Home Centre products online.
Each Return Voucher can only be used once. If you shop for less than the value of your voucher, you will lose the balance. So make sure you get your money's worth.