Posted: 16/09/2016 at 10:07
DFW that is a typical new build lawn, builders remove all top soil down to clay then during building it all gets compacted often with rubble buried in holes. Once up the gardeners come in spread a few inches of topsoil on the pan then roll out the lawn which is normally a general hardy type rather than bowling green. If it is hot and does not get enough water it tends to curl and in places die off. I watched it happen around here as they built on the old market gardens taking all the good soil away and selling it as part of their perks. Some give up and it becomes the children's playground some try too hard with chemicals others take it all up and start again, it is heart breaking.
Forget the four in one take the advice given by Verdun and Dove leave it to over winter then start again in spring. A mild wet winter would help it recover from the stress and build up strength for next year. Watch it during wet weather as the hard pan under the lawn can stop drainage, if water pools on the lawn it will need some drainage sorting out. The bad news is it will never be a bowling green the good news it can with care become a reasonable lawn. Spring feed and weed read the instructions on the packet and less is better, water it in well then wait six weeks and do it again, meanwhile keep the blades of the mower up, I keep my lawns at one inch, most lawns are not level so you end up shaving parts if the blades are set low. All this is probably not what you want to hear but that is gardening and over many years I have learned to make the best of what we have, perfection is an illusion.