If you received unusable results that you need to be rejected, please contact us and we will check your order. For us to identify these participants on our end and to be able to refund you, please send us the IDs of the users whose results you cannot use. 

You received user IDs alongside the answers in your survey tool if you activated the ID transmission from our end. If you are creating your survey at the moment, we kindly advise you to activate this setting in the first order creation step, as explained here.