You place an online order for a product. A few days later, the wrong product gets shipped to you. You contact the shipper online saying that they shipped you the wrong product; please ship the correct product and ask how to ship the wrong one.
The shipper answers (online) - They will ship the correct product and enclose a return slip for the wrong product.
A few days later you get the correct product but no packing slip. You contact the shipper about this, but there is no response. Every few days, you contact them and there is still no response. The shipper left no phone number and you have no way of locating one as the address is a PO Box number. The only way to correspond is by email or postal mail.
Q - How often or for what length of time do you have to keep trying before you may be allowed to keep the wrongly shipped product? It is possible that the shipper went out of business or moved which means that if you just ship it and pay for it (something that would be beyond the agreement, as originally the shipper agreed to pay for the return shipping but didn't include the return form) it may get lost, anyway.
Do the laws differ if the shipper was Jewish or Gentile?