We have an Iphone 4 that has been acting up. When making a call no one can hear me and we can't hear them, we are unable to listen to videos, and wifi keeps going off and on. Today we received an email from AT&T saying another GB of data had been added to the line because it had went over. We have 2 GB already on this line. I go back through my email and see I had received one Dec. 28th saying I was over too by a lot on the last billing cycle and another GB had been added. The phone apparently isn't using wifi even though it shows to be working. The phone is never used for than an hour a day on mobile data. That is only to check facebook. Would anyone have any ideas at all as to what could be causing the phone to have these problems?? Any help is greatly appreciated. The phone belongs to my daughter and she dropped it in Sept. and had to have the screen replaced and the home button hasn't worked since. This is when wifi got worse but the speaker, mic and data issue just started this week.