Touch screen is discalibrated and malfunctions

hello,

My sister has an iPhone 3g, and she has always been very carefull with it. She left it in the charger for a night, like she always does, and the next morning the touchscreen was malfunctioning. The slide to unlock, play music from the home screen and slide to turn off are all working normal, but when she wants to enter her passcode, the 3 button doesn't work, and the 6 and 9 select the cancel button and it goes back to the lockscreen. I gave her my old phone so she can use whatsapp and stuff. For her birthday in july she'll get my fathers old iphone 4. I want to know if there is a temporaily fix for it.

Thanks!