For mattresses.
Lian Meng Lu, off Beijing Lu, 2 blocks south of Carrefour near HSBC.
On east side of BJ Lu and south side of the road, there is a furniture mall.

In the mall there is a Kunming bed and mattress manufacturer's factory shop, on (I think) the first floor. They do a range of types of mattress construction as well as selling beds. These are to a range of western standards.
I can't remember prices off hand, but I remember thinking that they were very reasonably priced. Cheaper than Europe. Much cheaper than the western brand mattresses sold here in China (Dunlopillow/Silentnight) that do cost way to much money.

Hi mPRIn

We have had a few times that parcels from overseas didnt make it. We went to the International Post Office and went through the parcel lists personally and found them. If you havent done this yet then its definitly worth a try.

@shyam:

Mattresses can be found at many many places. An alternative is to get a foam topper. They may work or not for you, depending if you still like a firm bed or very soft. Prices of those may be less than a mattress, but I have seen some for several times the price of a new expensive mattress.

About buying large clothing:
Shops don't stock / buy them because they think they have a hard time selling them to the average Chinese. One of the tricks: try Luosiwan International Trade city (South Kunming). It is a wholesale market with thousands of shops but they get their products straight from the factories. You can find larger sizes there and if they don't have it sometimes they can request it from the factory for their next delivery and you just pick it up next time. Of course not all stores have large sizes but it may be easier with so many stores packed together (Luosiwan is South China's largest wholesale market. if you buy less than 10 items you still pay normal retail price, not wholesale price). Taobao may also have a +plus size section. Or search online for +plus size stores in KM.

I would always want to try before I buy. I have had Chinese +sizes bought for me, but they are still cut for Chinese frames.
If you buy from taoboa or Tmall, check the returns policy.
At Lousiwan you can at least try the stuff on.

Also, there is a new GAP store in Kunming, that has western clothes in western sizes. I will give them a go next time, as I usually have to get clothes when I am in Shanghai.

Yes, check the return policies of the Taobao and Tmall sellers. My wife often buys online and now and then has to send something back. So it is possible to return stuff or exchange it.

@Tiger Where is the GAP store?

Mattresses can also be bought at the second hand market. New not second hand for really cheap. We paid 130 kuai.
@Yuantongsi Thanks for the tip but these were packages lost in Hebei. I'll keep it in mind if I can get my mum to send anything else :D

Not sure on location, I was told by a coworker who has shopped there. I think he said Wangfujin.

Tailors are not very expensive in Kunming.