When it asks for your receipt number, just enter your name or any unique referance just in case its been used before.
It also says on the voucher there is not restriction to the amount of vouchers you can use per party so print away.
Complete a short survey(Took me less than a minute to complete) and as a thank you PE will create you a voucher for either of the above to enjoy with your next meal.
Whether you've had a great, average or disappointing experience at Pizza Express they would like to hear about it.
Can be bad, a little something for a little bit of your time. The survey is aimed at customers that have recently been but I am sure we can all recall a visit at some stage that can be reviewed.