Home Loan Prepayment Advice

I have a 25 lakh Home Loan taken from HDFC with 8.4% interest and 17 years tenure. I am planning to close this loan as soon as possible. I want to know if I can directly transfer the lumpsum amount at regular intervals in my loan account or have to go to HDFC everytime and sort it out. Also I heard how people increase their emi amount over the period, same question here also the little amount above emi, can I transfer it directly or need to involve HDFC ?