Do not unload into your own stock. Record the arrival state with photographs, take product core temperatures in several positions, download both the reefer log and the in-load logger before releasing the vehicle, quarantine the consignment rather than rejecting it outright, and notify the supplier and carrier within the contractual window.
Why the order matters
Once the pallets are mixed into your inventory the evidence is gone and the claim becomes a negotiation about memory. Once the vehicle leaves, the reefer download is in someone else’s hands. Everything that is cheap to do at the bay is impossible to do an hour later.
Assess safety and quality separately
For a frozen product, a short rise to -12 degrees Celsius is rarely a food safety event; it can still be a quality event through recrystallisation, drip loss and clumping. Run the safety assessment against your HACCP plan and document it. Then run the commercial assessment on the quality impact. Merging the two produces either an over-reaction or a waived claim.
The clause that prevents most of this
Name in the contract which temperature record prevails, who downloads it, and what excursion is tolerated in magnitude and duration. Most disputes are really disputes about whose thermometer counts. Details in cold chain management for frozen exports.