Do not do business at this shop and don't let a tuk-tuk or car service take you there. If a local, a policeman, or fellow tourist recommends you visit this shop, then he is in on the scam. He probably works on commission.
If you are extremely unlucky and end up at the store and purchase an items, then make sure you keep all of your receipt and the packaging. The receipt they give you will say "no refund", but there will also be a clause for a "70% refund." In the pictured case, the store manager has crossed out the "70% refund clause." The best way to get a refund is to get someone fluent in Thai to return with you to the store and demand a full refund. Try not to settle for less than 90%.