We have just had a decorator paint our upstairs. He wanted to purchase the paint. We explained we wanted the exact shade we had downstairs and gave him a tin of the paint which he said he’d colour match as he didn’t like painting with that brand. He informed us he had an exact match. We came home to find the shade is much yellower than the one we have downstairs. Where as that is off white magnolia, this one is really yellow. What should we do? Any advice welcome. He’s coming back tomorrow to do the woodwork but the top coat is now complete in all rooms!