I would be grateful for advice as to where would be the best place to part exchange mobiles. I would like to sell my Samsung A7 (First edition) which is about 10 months old and buy an Iphone 6s. I think the value of the Samusng is around the 3-4000 baht mark albeit I paid 12,700 baht in March this year.

When buying the Iphone how do I ensure it is not one of the imports from Hong Kong, which I am told have a very limited guarantee period.

Many thanks

Best is to try private sale though you will hear from many scammers on Craigslist. Most shops in MBK. the largest phone marketplace will only want to pay 1/3rd of value. You'd be lucky to get B3000 from them. Phones get old fast these days.

You might have more luck trying neighborhood phone shops. A friend was selling a Samsung tablet she had won as a prize and didn't want. She went to a neighborhood phone shop and got a very good price...about 2/3 retail. In this case, it was unused and in perfect condition with all packaging but it still might be worth wandering around a bit. It will help if you have the original box and packing materials.

Why not try the free classifieds on ThaiVisa?