Watsons Online Order Cancellation and Address Change Issue

I just ordered something from Watsons online, but I made a mistake and chose the wrong delivery address. I'm really disappointed about it. Even though I realized my mistake as soon as I placed the order, I ended up stuck in a really annoying situation. I was surprised that I couldn't cancel the order or change the delivery address. It was so hard to find a customer service rep who actually responded to help me. It just made me even more annoyed. I've had problems with Watsons' online shopping before. It's obvious that they are really careless when it comes to dealing with online orders. I was so frustrated because they couldn't handle customer issues properly and it was so hard to make even small changes to my order.