Iphone won't charge says accessory not supported?

Hi, i'm a student, so buying an 3gs kept my savings of a year.3 months ago i buyed an 3gs.
2 weeks ago 1 nite i recognized n was shocked that its volume buttn is missing… I took it to istore and they told me that its a case of missing part and so we cud not help you. The gave me an alternative that we could replace it for 10500rs.
ofcos thts half the cost just for a button so i left it.
i told em its wrong if suppose i had the detached button it would me your fault n now that i don't have the *** key its mine…
they just made me sign something that i'm satisfied and thats it.
now my phone isn't charging, it says that the *** chargr i got along is not a supported accessory.
its now off n iim feeling ill with my decision of buying an iphone.
i have no hopes that they would help me this time too.
i wanna know what service would i get, if i go now, and is it here only in india tht the apple service is so ***.

Added (1). I can't even sell it as it woud give me a total loss as the phone isn't evn switchin on, whu wud buy it

Not only in India, Apple's services are like this only in all over the world.
I would like to suggest you that instead of spending money on iPhone just sell that device away and go get a Nokia device because their customer service along with the performance of the device is very good.

My iPhone brings up the same message (even with the charger it came with) but it doesn't do it all the time so its a bit weird! Sometimes I have to sit there and plug it in & out 20 times in a row before it'll charge then it'll come back up after 10minutes! So annoying!
The other night I just left it with the message up & still plugged into the charger & it did slowly get up to 100% but took all night!