Thig kind of problem does happen with BSNL. When i used them i also faced this and this is the reason i mainly changed my ISP. Their are sometimes when i need to access some sites for some urgent work but then i see i cant do it because BSNL wont let me do it.

Don;t worry you will face this problem for some time and then it will go and then you would face this problem with some other sites after some time.