Refusal to call manger

After my last visit to repair shop and i've been told my tablet cant be fixed I have to buy a new one, I returned to the repair shop to give me a letter to state they don't repair this specific tablet for my personal insurance. I was then told this time I have to book it in for 3 days to get the letter from head office because they are not allowed to say its not repairable. After this great news I told Carlo straight thanks for the useless service once again and started walking out. Then thought, no. I turned around and asked him to call the manager with wich he responded \I won't". I then told him to call the manager and he responded \"" I will not serve you"