I signed up to Bounts earlier in the year. It's an app that tracks how much exercise you do (mine is linked to my FitBit and also recognises when I go to the gym). You accrue points and are supposed to be able to exchange them for vouchers. I thought it sounded brilliant as I would essentially be being rewarded for exercise I was going to do anyway!
However, the reward vouchers never seem to be in stock in the their shop. Any of them. They are supposed to stock Amazon, Sainsburys, Starbucks etc, all kinds of stuff that I would love to be able to buy...but they are just never there.
I emailed them and they assured me that they restock daily and I need to keep checking back. 
You can be a free member, which I am, or pay £9.99 a year for Premium membership and I wondering if they are keeping back all the vouchers for Premium members.
Does anyone else use them and have you had better luck getting hold of a voucher than I have?