Guy this issue has been well discussed at WP, at other forums, inside ptcl and wasn't solved. But now its kind of addressed. You will now be able to change your password of DSL without calling helpline and telling your old/new password to the CSR. Infact now by webportal.
Note: This is under process so your user may or may not exsist on the portal. Hold your horses.
Currently only 9% users can do. Keep visiting this link for updates. And force this a bit to 1218 so that they make it quick