No, you shouldn't have been more polite Chloe.
I think your mistake, if anything, was offering help a second time after he had said you were being rude.
I'd have shut the door in his face and immediately telephoned the company -perhaps I'm unnecessarioy suspicious, but my first thought would have been that he wasn't actually anything to do with them.
Hope you are ok. 
Thinking of selling due to heat


