Posted: Today at 13:58
I'm afraid I agree with Esspee. I don't think that looks like a quality 'product' at all.
The turf should be uniform, there really shouldn't be lumps of different grasses in it, and it looks badly joined. You'll need to water well (unless you get a week or two of rain) to keep the edges moist until they join properly.
New builds are notoriously bad for having poor soil because builders chuck everything down and cover it. It may not have been very well prepared before laying.
It's really up to you whether you question the supplier about it, or whether you want to sort it yourself. It largely depends on how much of a survey he/they did initially, what he told you was required, and what you were charged. Filling the gaps with some soil and firming it down will help, and then reseeding in spring. It's probably too late to seed now unless you're in a warm enough area to get quick germination.