Telling the lab the speed you shot the film at is pretty pointless, because most high street labs don't give a monkey's.(posted 8202 days ago)
I notice that a lot of cheaper labs are overdeveloping their C-41 these days. That could well be the problem here.
Pushing C-41 gives higher colour saturation, which pleases most of the morons that use (and run) these labs, but it makes the highlights unprintable and the grain increases enormously.
Find a better lab, or process the film yourself.