Help Can not send Multiple sms

[anupdada]

Hi I am using HTC wildfire S and using stock ROM.
Andriod version: 2.3.5
HTC sense version: 2.1
Software no.: 2.26.720.3

I am unable to send multiple sms at a time or msg more than 160 characters. I get error as unable to send sms after multiple attempts. I have checked sms center no. and it is correct. I have tried other netwok sim cards also but get same error. But on other cell sms goes without any problem with same sim cards.
After talking to HTC customer care I did factory reset but it didnt help me. Not even that, I have also installed new RUU i.e stock ROM but get same problem. Is there anyone genuine smart engineer here who can solve this complicated problem of mine?

 

[anupdada]

I don't understand one thing about thin site. Here no one helps. what type of forum site is this.