By following our step by step measuring guide and discussing your order in detail with our sales team we really hope that this should not happen. Please do contact us if you have issues when installing the blinds as we may hopefully be able to advise a way to get them to fit – however due to the bespoke nature of our products we can not accept returns. Please also be aware that if you change your windows after taking your measurements and placing your order, we can not guarantee that the blinds will still fit!