Tata Photon Plus — worst service in excess billing

i have bought tata photon connection just months back n i have payed an amount of not less than 15 k till today.. i tuk up aplan of 500mb den i realised that i would need some other plan i called up couster care n told them to change my plan... and i was told that the plan vill b changed before evening.. but which was not done at all.. n dey disconnect the connection every 2 days ones

Wen i ever i call up couster care i never get proper information on anything.. dey tell is is our network problem vill give u connection in 4hrs but which never happens... after i call around 10 time n den tell them to disconnect dey tell v r sorry for inconvience caused n tell me v have disconnected bcz u have crossed ur credit limit..n they always give worng figures... I m told that my credit limit is 2500 n n once i called couster care just around 10 days back n dey said my outstanding is 8000 n i should pay it asap for continued services..
beofre all this i had requested for a cancellation of my account n i got a call for reconfirmation ver in i was promised that the paln vill b changed with in a day v vil b providing first 100 minutes free from the next billing date n also vill do a wave of extra charges n i vill b charged according to the plan i have asked...

but none of the promises r taken care of n i doubt that i have been charged tooo much.