Macbook late 09 cracked near touchpad

Hi, my macbook a1342 late 09 white is very well looked after but has a crack that goes from the corner of the trackpad to the bottom of the case, this started out when the macbook was only 8 month old and has got bigger. I have never done anything about this but reading on the internet it seems like this is a common problem, my macbook is now out of warranty about 23 month old, what i would like to know is, is there anything i can do to get apple to fix it free? how do i go about contacting them etc?