What utter incompetence on the part of the tech, or more likely deliberate bullshit. He must think you are stupid to try that ridiculous 'S1' argument - how rude it that? F***ing wanker.
This is an appalling story!
First rule in trying to solve a problem - try and deny there is a problem. And even if there is, it's somehow the customer's fault! Gawd 'elp us..
I would write to the dealer and say (in effect, don't use these words.. ) "Look, legally you have to give me a re-fund. If you don't **** me about I may well spend that re-fund in your shop. If you carry on the way you are, I'm off!" And send a copy to customer services at H.U.K.