Hi! I understand your frustration, absolutely! Its not uncommon for people to reject rematches or draw offers even when its dead drawn! Guess its just the way of blitz and we have to get used to it. However, just for info, the general guideline of good sportsmanship should be to give at least 1 rematch, i.e. to say a rejection second rematch shouldnt be met with too much fury! Just relax, and enjoy the game!
if YOU lose then the opponent asks a rematch then you could just say that you think you should have some more practice before you replay them, but otherwise it is common decency to accept a rematch.
I hate them. I really do. Within a nano-second of the game's ending they're playing someone else. Why?
(add to this internet chess players who decline draw offers when triple-repitition is imminent and then proceed to repeat the position).