Sinoz Sunscreen from Watsons Defective – Requesting Immediate Return or Exchange

I purchased Sinoz sunscreen from a Watsons store based on the recommendation of the staff, but the product's texture and color were defective. I am requesting either a return or an exchange. I complained to the store, but they refused to take it back because the package had been opened. How am I supposed to know the product is faulty without trying it? I expect a positive response and resolution as soon as possible. This is frustrating, and I hope Watsons can address this issue promptly.