Why is it so hard to find a warm dress for dgd in February?

I have a 6 year old granddaughter and have been looking, unsuccessfully, all day today for a warm long sleeve dress. Should be simple given its early February but I have failed to find anything other than skimpy summer clothes which the assistants 'helpfully' suggest I buy a tee shirt, cardi and tights to turn the said summer stuff into a winter outfit. I am Aware of the fashion industry which works months ahead but it's bitter cold now and will be for many months (sadly) before we get our moment in the sun. Is it unreasonable to expect that a huge shopping centre like blue water with its 3 large department stores as well as many others cannot stock suitable children's clothing? I notice it's easy to get ladies long sleeve dresses in all shops.
And while I am on the subject of things annoying, why are child car seats and push chairs so hard to fit/open/collapse?