Just noticed Iphone 4S wifi problem

HI, I just received an email from ATT that I used 65% of my data for my measly 300MB plan... I found that quite odd as I only use the phone in wifi hotspots or at home, so I barley use any ATT data... What I noticed is after the last update I cannot connect to my personal home WEP network anymore... It says "unable to join the network rcflex" then just gives me a dismiss button I don't get any option to enter a network security key...

Any help would be great