Barclays Finance. — Abusing when not done EMI payment for one month

I had taken loan from Barclay's Finance in Feb 2009. I regularaly make their payment in EMI of Rs. 1521.00. But they had given agengy to Striker Finance.In the month of feb 2010 , I had not done their payment on time, but I told them to take payment in next month along with next month's EMI of Rs. 1521.00. But, Striker Finance people are abusing my family member at my home when I was absent. When I called the head office then they are trying to forcefully stop me from doing any complain regarding this.
So, I wanted to take some action regarding this, and give me the appropriate penalty for the same.