One of my current opponents, " 

SUNiLL

" has won his last 25 games in a row, this seems unlikely for any player. How do I check to see if he is not using a computer chess programme to help him?

You are not supposed to raise questions or cast aspersions about opponents on these forums. Anything of that type, you need to create a support ticket. (Click the Help and Support link on the bottom of every page.)

Have all the opponents been rated at the level he/she is at? If so, they would have gained about 400 pts over 25 games at 8 pts/game.

If the opponents were mainly much weaker, then you know that the player values a win more than a good game

Just looking at those games, the majority of games he is playing are at least 200pts below him. I can usually beat people 200pts below me no prob at all. It is fine to assume that the few times he is playing against people of his own strength he has won a few in a row. If he was constantly beating 1800+ 25 in a row, then I would start to be a little suspicious.