I bet they are hoping you'd give up and go elsewhere. If you sent it 3 times and still not fixed, or come back with different issues each time, it is clear indication that they either don't care or don't know how to do it correctly. Sending it one more time won't resolve the issue. If it did, it will purely by chance.

At this point, I would be demanding my money back or file a claim at a credit card company and send it elsewhere.