Bankers and financial institutions are partial towards new customers then the existing ones. In fact, they are greedy and offer teaser rates just to grab hold of new customers. Teaser rates no where means that you are a privileged customer, all it means is that they are offering you same so that they can trap you once and for all.
Once you take a loan at teaser rate, they will keep on increasing your rate of interest. If you get frustrated by all this, they will not let you take easy way out. You try to switch your loan to another bank or prepay it using your post-tax savings; in both the cases you will be charged prepayment penalty. It's a vicious circle you are caught in, so beware.
That's what I conclude when bankers first refused RBI's suggestion to withdraw prepayment penalty on loans and now they are not ready to extend cheaper loan rates to existing customers.
Lesson from this, bank don't give you loans so that you can become rich. They lend you money so that they can have excellent balance sheets. Think more then twice before applying for any kind of loan.
If some one claims to love your money as much you do, beware, because it means they are planning to take it all from you.