I'd complain to Quidco, Unclegeorge. (_;) Mine was paid today too (from the previous time they were offering £6 cashback) and that went through at the expected amount.
Paid today £1
If the cashback doesn't "track" within a day or so, you should submit a claim through Quidco's support pages - log in to your account, click on Support and then "Create cashback claim".
i do not really understand how it works. I've done the registration and i see nothing in quidco... :/