Ikea Duvet cleaning

Dry cleaners. I know you said no. But My mother in law does swear by borax she says it gets rid of all smells

it says online does not recommend dry cleaning for duvet. I will try use borax tho at home!

Does it say why because I’ve had it done a few times

I do laundry stripping on all my bedsheets about twice a year and it helps so much. I also use borax in my laundry stripping.

what is laundry stripping?

it says the harsh chemicals are not good for the down

Laundry stripping is an aggressive form of cleaning your laundry that removes built-up soil, body oils, sweat, and grime from the individual, tightly-woven fibers of your clothing. 
You literally fill a bath tub of very hot water, laundry detergent, borax and washing baking soda along with your laundry and leave it for about 6 hours stirring occasionally. It is so gross how the water turns to black. I usually only strip clean laundry and the water still comes out black. Then you just wash your laundry without detergent in your washer to make sure all the detergent and stuff you used during stripping comes out.
I follow the recipe from go clean co.

Fold the thing in 3 lengthwise. Then fold in up in a "s"shape and put it into your front loader. If you have top loader skip the second step and feed it around the agitator instead

This will let the entire thing get washed