Social activist Anna Hazare on Sunday attacked Prime Minister Narender Modi, saying he has failed to fulfill promises made to farmers and on the Lokpal.Hazare said he will start a 'satyagrah' on March 23 in Delhi to highlight the problems faced by the farmers, the Jan Lokpal issue and the need for electoral reforms."I will fight for farmers and Lokpal," he said, adding that he was sitting silent on these issues for the last three years but trying to communicate with BJP-led Central government over them.But nothing happened, he said, noting: "I have written 21 letters to PM Modi but did not receive any reply till date."