How to check balance

Hi,I have been using Tata Plug 2 Surf USB modem for the last 18+ months, which is a pre-paid one and I keep recharging it whenever I need it to access the net. The software for accessing the net keeps crashing all the time whenever I click on the SMS icon and this has been the case for more than 6 months. I have uninstalled and installed it 10 times but the problem is still there. My pc runs Windows XP with a genuine version and fully firewalled and virus protected as maintained by the company. Which number I should call to know my balance on the modem? I have been given this number 9220012524/9220012345 but they seem to be serving only customers who have both the Tata mobile/landline and the Plug 2 surf modem. I only have the modem and not the mobile or landline. I am tired, please help me. Thanks