I had a mixed feeling and experience with IBSN. I filed my US returns through IBSN in 2009 without any issues. So far so good. But in 2010, things went really bad. First, I sent my papers via post and there was no ack. Multiple emails to them were not responded. Then I contacted Laxmi P by getting the email id from here. It took a long time to get an result, but ultimately, things turned out good and my case is settled.
Thanks Laxmi for his personal attention on this matter.