You can purchase Gift Vouchers by following the steps below on tmw,

• Click on Gift Vouchers Icon in tmw App
• Select on the Gift voucher which you want to purchase and choose the quantity
• Accept the terms and conditions and click Proceed
• Click on View in Enter Promo code field to choose any discount offer available
• Click on Pay

 If you don't have sufficient amount in your wallet then you will need to load and pay.