I guess you are the buyer of the film and your pictures have not been developed ?
You complained to the seller who suggested your camera was faulty.
If so and you are within 30days of delivery to yourself you can open a not as described case under the mbg for a refund.
If it is after 30 days - put it down to experiance - I guess it was inexpensive - you can try your card provider but is it worth the hassle - who knows why the developing did not work - could be many reasons - hardly worth an argument !