Bit of a moral dilemma. Trivial, admittedly, but I'm happy to let the MN jury be my guide.
I bought a pair of boots from M&S online. Full price £95. There was an online only offer on them and I got 40 % off so saved around £35. They don't fit, so they're going back, and the easiest way to return them is to take them to a store.
If I take them back without a receipt they will give me the full price in store credit and I'll have made £35 profit. If I take my receipt in, I'll get back what I paid. I'm not on the breadline, I don't need the money.
People of Mumsnet, what would you do?