Going based off what context I have, the way I made sense of this was to fragment it into two parts, particularly where the comma makes its appearance. This helps separate the clauses.
So, 製品が完成した場合、is referring to a situation in which the goods in question will be finished, and could probably be translated as something like, "When the product is complete..."
製品出荷から返済させていただけますでしょうか This was one where I had to do a literal translation of the text, but I think "Can I perhaps be repaid after the final product ships out?" is probably better than "can receive repayment from final product shipping perhaps?"
I realize translations like this don't exactly do much in the way of helping make sense of the structure, but this at least gives you the right idea of what's being conveyed.