As above all good advice.
If vehicle has a printer, also make sure you take a printout of your temp before you unload anywhere and before you open your doors.
I worked with fridges for years and the only times I ever had a problem was when they have probed the goods 20 mins after unloading me and left the stuff sitting outside before probing it. Printout proves you have done your part.
If you get refused due to a probe fail, ask to see them do it in front of you. Can be faulty equipment or badly trained monkeys at fault, but often there is no reasoning with them anyway.
Once got a load refused, probe guy claimed temp was 15°c.
I explained that the last time these chickens had seen 15°c, they were alive and flapping. Showed them proof of journey temp since I had taken them out of blast chiller at slaughterhouse 6 hours ago and it was a constant 1-3°c the whole journey till they opened the doors. Refused to let me see them probe it, refused to let me use my own probe, all due to H&S. Load refused but I got paid twice as the customer sent the exact same load in the next day lol