While the connection is really worth and delivers what is promised, the sales staff is really bad. Always check your plan as soon as the installation is done and fill up the form carefully.
In my case the salesperson screwed up something (could be in order to achieve his targets), and a more expensive plan was activated for me. I am still waiting for the customer care to fix this up.
Never pay any cash to the sales person. In my case he took the cash payment after connection was installed and never deposited the money to Tata. The payment was made for installation charges and refundable refund able security. Obviously he promised but never provided a payment receipt.