Help recently had a white pvcu consevatory built. However the roof is a different colour white(very noticible) the builder says he got it from a different manufacturer. what can I do?

you mean the colour of the upvc in the roof is different from the colour of the upvc frames below?

This is not that unusual - there are only a limited number of roofing systems which have matching side frames (as far as colour goes)

There is WHITE and then there is "white"

In most cases this "difference" is hardly noticeable - but that is clearly not the case with you.

Do you know the brand of upvc frames used in the bottom? and the brand of conservatory roof used?

Personally I find most reputable conservatory suppliers are aware of this "issue" and usually get a match that is "close enough" to not make any difference.