Bangkok Big Mango

What are your recommended shopping malls in Bangkok for clothing?
I am visiting Bangkok to do some shopping. I went to Tesco but the designer clothes I got were expensive. Can someone tell me where I can buy quality yet affordable clothing for adult women? I also need to find clothes big enough for tall Westerners since my boyfriend has a hard time finding clothes that fit him.
I’d also like to know where is a good place to buy fruits and other food stuffs. I’d buy them at the fruit stands but I have no idea what the prices of mangoes, etc. really are. Is Tesco relatively cheaper or more expensive than other malls? Does it give a discount or VAT refund for tourists? I read about it but haven’t tried it yet.
Perhaps posting this in the Thailand section will get you some more informed answers.
Big Mango Bar New Year 2009, Bangkok