iOS bug - challenges messed up.

on the iOS app, whenever I issue a second challenge after opening the app, a certain player is challenged.  Not by choice - because of a bug in the server data.  Uninstalling/reinstalling does not repair the problem.  This happens after I issue one challenge, complete the game, and issue another challenge.  As a result of frequent challenge cancellations (because I don't actually endlessly want to play that same guy - and, moveover, he isn't always online and iOS offers no way to cancel a challenge "for free" even if it is NEVER repsonded to), I have been penalized, so that I can only attempt to play once every five minutes.  So, if I forget to close the app after each game, I have to wait five minutes to try again.