Did you try doing this AFTER first hitting "Forget this Network"? If not, you might want to give that a try. If after doing this, you still can't connect, I'm sorry but I have no further suggestions. Since it's not your network, obviously you can't change the encryption being used. However, just so you know, WEP is like using no encryption at all. There is software, readily available, that can crack WEP encryption in seconds. iOS devices don't play well with WEP. For iOS devices, best to use WPA2.