After having received a 200$ drone from banggood, I realised that the transmitter didn't work. I was afraid I had to spend 50 more dollars to buy another transmitter, so I sent an email to the customer service reporting the issue.
To my relief, I received the reply the day after.
Not only did they let me choose between a refund or a new transmitter but also allowed me to keep the broken one so that I will have repair parts for the transmitter.
I hope all online shops worked the same.