Speaking to the media on Monday evening, Wehrle said: "If you really want to sign a player, you have to be able to reach a solution during this period. We're playing the Super Cup on Saturday.
"Everything should be sorted out by kick-off at the latest. It's now been six and a half weeks. At some point, enough is enough."
If a transfer does not go through by the time the game begins, the rising star will be considered "not for sale."