I’d double-check with your guy. I took those prices directly from the Ford website:
https://www.ford.co.uk/shop/price-and-locate/bp/ice#/model?catalogId=WAEGB-CF7-2020-PUMAGBR202175
Check the price differences for each colour between the ST-X line and the Vignale.
Also:
https://www.vanarama.com/guides/cars/ford-puma-colour-guide