Hi! Hard question to answer really as it is most likely their fault for ordering a size that they didn’t check the dimensions of! Depends how you want to handle it really. You *could* offer to send a different size free of charge (at cost to you, but maybe a good review to boost the store) or just refund and take the hit. Doesn’t sound like anything you’ve done wrong, but it’s how you want the optics to look. Maybe offer a refund first and if they still want a print you could offer a specific discount code for them to use so you at least get some revenue from them buying the correct size? Even if it’s 50% off a different size, it would still probably be a cost to you, but again, you might get a good review out of it.