I'm afraid you won't be able to cancel any of these contracts on the basis that the cashback hasn't been paid. Quidco isn't party to the contractual process, and the cashback is never guaranteed. There are, however, a lot of people unhappy at Quidco's failure to pay out large amounts recently, and it's starting to surface on the net. Here, for example: Quidco Follow up thread 14 - MoneySavingExpert.com Forums