I recently bought the Bayangtoys X21 drone!
It worked really well - though the instructions are quite hard to read - I had to use youtube user reviews.
I tested it out in my big backyard. On the second flight, I decided to use the 'automatic return to home function'.
The drone circled away from where I was/where it took off from, and right into a tree 15m away. It shut off and hit the ground - not broken, but the battery had come out.
When I retrieved it, the battery 'exploded' and bust into flames - like this video, totally destroying the drone's internal components and meting the casing. The amount of smoke was incredible, I had to sprint away from the smoke. It was really dangerous. If that had happened inside my house, my whole house may have burnt down.
Here's a picture of the damage.
Should I request a refund? While I did decide to use the 'return to home function', I did not expect it to crash into the tree (that was out of my control). The drone was far away from the tree when I decided to use the function - it had to move further away to get there! Also, it was not this fall that broke the drone, but the battery failure.
Contact them
GB isn't an Aussie store, so ACL doesn't apply. Whatever resolution they offer is about the only option available.