Plascon paint.

Bought a base paint that was mixed for me today at Builders. There is only 800ml in the tin and the salesman told me due to the base that is to be mixed to colour. These base tins have less in for the mix etc, but it does not come to 1l once mixed. Yet if i buy 1l white velvaglo it is what you pay for 1l, not 800ml. Yet the mixed colours are more expensive but for less paint? 200ml of paint is quite a bit if you need to cover the last bit of wall or cupboard you are painting... bit of a ripoff ... there is a form on contact us for Plascon SA but you cannot submit it - not much use for it either.