Here is the page of Hostelworld retailer
20 Points / £1

Hostelworld is the world’s number one hostel booking website. Since launching in 1999, they have become the leading provider of online reservations for the budget, independent and youth travel market
Earn rewards on your deposit only. No rewards earned on payments made at the hostel.

Queries can only be investigated after your booking (stay) is complete.
Rewards are not calculated on postage / handling / delivery costs or associated purchase taxes in your region (This may include but not be limited to VAT, GST etc).