Changing tenure of a personal loan

Hi

I applied for a personal loan in HDFC one month ago. I talked with the executive about the interest rate and tenure details. Finally the interest rate is fixed as 11.49% for 4 lacks and I chose a tenure for 3 years. The documents are collected and processed. After the acceptance of the application, I got an SMS about the tenure and priciple amount details. Unfortunately I paid no attention to it, since it is an SMS. As of my knowledge the bank have to call the customer and tell about the details like principle amount, interest rate, tenure, etc. But I didn't received any call. Within few hours executive came with agreement and I signed it (since I spoke about the interest rate and tenure with him already). The agreement is empty when I signed it. Finally the loan is disbursed not for 3 years but for a tenure of 4 years. I called the manager and requested to change it to 3 years. But he refused.

My questions are,

Is it legal to disburse loan without a call confirmation?

If not, is it possible to insist the bank to change the tenure legally? 

Thanks