You can change your PDCs but you will have to give new PDCs with an application to the lender who will then return your earlier PDCs. Some banks offer enhancement of the loan amount after they have repaid part of their principal. You can go in for a higher loan amount as per your new eligibilty. Moreover, you can get a preferential pricing on your new loan amount. No, it is not at all necessary that you have an account with the bank, but some companies do give a discount if you are already their customer.
Companies ask for cheques of local-bank.
You can either go to a bank or to finance company and get the application form and information of schemes and formalities, or you can call them and they usually send their agent to your house. The finance company at first notifies to the borrower whenever the cheque bounces. If on such reminder the borrower doesn t pay the EMI the lender approaches the refrences provided to him by the borrower. Thereafter the finance company can go to the courts against the defaulter to recover their dues.