[Resolved]  Airtel — Service reply after every sms/call

Hello,
I have an annoying problem with my Sim card. Every time I send a message, I receive a service reply. Every time I call also. As I have the 150 sms free plan, I send a lot of sms per day. Long one. If I send around 500 characters (4 sms) in one sms, then I will receive 4 times the service reply... Just to tell me that my balance account has NOT changed. I could forget about it, if it wasnt using my "received sms" tone! To cancel it i just press any key, but 4 times it will come, so 4 times I have to press any key.
I just want to cancel the service reply. I looked on the internet and it seems that it's not a common problem.
Is there anything I can do against that?