I understand your frustration mate.
Facing a similar situation in the league with my 2nd team.
This guy put on his good team against me and cost me the match.
Currently, the league is tied on points and Im yet to play this idit a 2nd time, whereas my competitor got big victories against him.

I did write to Nordeus about this, but all i got was that they dont consider it cheating (even though it is unethical).
Apparently, there is something in works to counter this, but no further details were provided.