With the best will in the world, counter staff often have no idea what’s going on (though Managers obviously should.)

I struck a new counter person the other week; they refused to lodge my pre-paid letters with tracking, because I had removed the back tear-off (“sender to keep”) which I was presenting for hand date franking. They said they had to remove the completed tear-off themselves so they could check that the address on the front of the envelope was the same. I didn’t bother arguing with them; I just stood aside and waited until one of the regular staff was available. Fortunately they only seemed to be filling-in for that day.