right now am in power on and on 128kbps plan,

the download speed is equal to upload speed in tata, i have validity up until march 25th 2009, however i would like to change to 512kbps unlimited plan now,

what should i do, i tried to contact the sutomer care they were SIMPLY IGNORANT, terrible almost,

so please let me know on what i should do to change the plan to 512kbps, btw i am from coimbatore