Bubble trouble - Bubble Trouble company is doing fraud

I have purchased pyro gun with its refill on July * **** and yesterday i.e. July ** **** i received the package. But Pyro gun received in that was fully rusty and old,we can say it was already used by someone else earlier. When i check with company they said product is non refundable and they can only do the replacement but for replacement customer has to pay the courier charges. Why customer has to pay courier charges when there is no mistake from my end.