I would say yes but it depends what it is and how long after purchase, original packaging and payment receipt.

 

Here is the return refund for items bought online with their rules. I guess the same would apply to things bought in store.

https://corporate.lotuss.com/en/faq/shop-online/

1. Customer can return the product at the customer service counter at any store within 7 days from the date of receiving the product.
2. For fresh products, customers may return the product within  the next day after receiving the product only.
3. In case of refund, delivery document or purchase order document (email) is required.
4. In case of refund, you must bring the products you want to return and follow the   conditions set out below.
   4.1 In case of partial refund, customers are required to return the products which they want to refund (including the premium items) together with document set out in 3) above in good condition and unused.
   4.2 In case of wholly refund , customers are required to return all products (including the premium items) together with document set out in 3. above in good condition and unused.
5. Refund will be provided in cash only.

Basically, yes.

In reality, after multiple conversations in Thai with customer service, we gave up and threw the wrong and defective (yes, both) item in the garbage. The money is not worth the mental effort. 

I have done it at Lotus's in On Nut.  I cannot speak Thai and their customer service was excellent, plus I had already thrown the receipt away. 

But your experience will vary depending where you go.

Just try, all the big ones have a dedicated customer service counter.