Answer:
The sim card may be tampered already due to you having exceeded the normal data usage limit for the sim. Did you download big files during the process? If yes then thats the more likely reason. Another is that your phone is having some technical malfunctions.. Kindly reboot to see changes. If not satisfied call CSR via the sun sim through dialing 200 and filing your problem. For them to resolve. Also there are threads here on how to fix your issue.. Kindly search the site in your convenience. Hope this helped you.. If you need any more assistance kindly let me know. Thanks and Merry X-mas.