Poor return service

I ordered paint spray gun, delivered was quite on time. I opened the gun, put in the paint just to realise that it doesn't work. It cannot suck out the paint, i emailed snatcher intold them i want to return it. 1. They sent a courier guy without telling me. 2. They said if the spray has been used, they wont refund or replace it. I mean how was i supposed to test if it works or not? If its not by putting in paint? I regret buying from snatcher, i will not encourage anyone to buy from them.