Mywatchsales.com - Delivered wrong item

I had ordered a watch from mywatchsales.com and I received a wrong item. I received the item on **st of March I think. So I spoke to the **x* chat service executive and he said that the delivery boy will be sent to pick up the item and replace the item right away. They said it'll all be done by **th of March. The very next day the chat service had been disabled for my account. I tried from different accounts but the chat service was still disabled. I tried from another phone and I was able to chat with the customer executive. He asked me to wait and that he'll check and let me know but after a while, the website got refreshed and the chat service was gone again. The only way to reach their executive is either by chat service or emails. They didn't respond to the emails and they're blocking me from the chat service. I am frustrated and I want to sue these people.