25 KBps is good enough if u r far away from your exchange. Otherwise chk ur lines and junctions etc. and cable quality. Or maybe MTNL's service is not that good. Many get lesser speeds. I get around 30 to 32 KBps as I'm close to the exchange - within 1 Km. Still applied the tweaks. Expectedly, no change. Thankfully it didn't get worse.