Major credit cards are usually accepted in the main stores for larger purchases, but cash is preferred for small items and smaller shops prefer cash. Traveller’s checks are also accepted, though the rate that you will get is less favourable than at a bank.
By law, shopkeepers must give a receipt, which you should keep. If a purchased item is defective, most shops will change the article or give you a credit, as long as you show the receipt. Cash refunds are not usually given.