Used QUID30 and the cashback offer. 3 x £15 games came to £26.65 delivered in total, assuming tracked cashback pays out.
The cashback percentages given by Quidco should be viewed as a guide only.
I've tried several times to deduce from which figure (excluding or including VAT, postage, discount vouchers/coupons etc.) they calculate their cashbacks and rarely does it appear logical. The summary is - in my opinion - if you get a cashback then that is fine, but we shouldn't make purchases based on it.