New windows and Door are draughty

Forestjoe

@boohoo They haven't failed they still work that's the product they bought, dureflex doors are built to cost as little as possible, builder probably payed less than £150 for that door and fitted it incorrectly which is making things worse.
@justinscot yes putting a bigger gasket in would help. Usually pressed in but they might have glued even if they have you can pull it out and clean chanel with sharp knife. Might also want to drop a spirit level on frame and door make sure it's level and upright and doors not bowed. 

JusinScot

Forestjoe said:

@justinscot yes putting a bigger gasket in would help. Usually pressed in but they might have glued even if they have you can pull it out and clean chanel with sharp knife. Might also want to drop a spirit level on frame and door make sure it's level and upright and doors not bowed. 

I want to try to change the gasket but this gasket does not look like the replacement gaskets i find for sale. 
IMG_20200917_102615.jpg
It has a thin strip in the inside, then a groove and a thicker strip on the outside, both appear to be glued in. Something 2mm thicker should seal the gaps. What are my replacement options?
thank you

Boohoo

That looks like flipper gasket.
Have a look at this link for gasket types/options.
http://www.double-glazing-parts-repairs.co.uk/category-gasket
I am not sure what Forestjoe is on about but i can not see you mention the door/window manufacturer in the OP.
As the door and windows are under 7 months old they should be under some sort of warranty so you should try to get them back to do the work. 
If they wont or have gone bust you can try your credit card company for help in solving this matter BUT only if you have paid using a credit card for the items to be fitted.