1. Contact the customer to verify: First, you can contact the customer and ask whose signature or abbreviation it is. If you can prove that the signature or abbreviation is actually signed by the customer, then you can discuss with the customer how to resolve the dispute.

2. Check the agreement or contract: If you have a written agreement or contract with the customer, you can check the agreement or contract to determine whether the signature or abbreviation conforms to the provisions in the agreement or contract.

3. Check the evidence: If you can provide other evidence of the signature or abbreviation, such as receipts, invoices or other documents, it may help to prove that the signature or abbreviation is signed by the customer.

4. Consulting a lawyer: If the dispute cannot be resolved, you can consult a lawyer for legal advice and learn about possible legal channels.

The best way is to ensure that the customer is required to sign a complete bill of lading at the time of delivery to avoid similar problems.