Procedure to apply for bail in motor accident cases

I got involved in a minor accident a month back. We were driving our car and by mistake while crossing road a speeding motor bike hit us and he fell down. There was a old lady in the bike who was injured as well. We then took them to hospital and in hospital they said it was just minor injuries and not so serious and treated them. We also paid the necessary compensation for that, however they made us to write a letter stating the same. we wrote that we paid so much amount and settled, and if in case there are any further problem they can reach us . We just wanted to leave the scene as there were too many people in the place. Now after a month they are calling and asking for more money stating that there is more to pay or they ll file a case. I asked them to go a head with filling a case and we ll deal if they file and I blocked the number. Kindly let me know on actions to be taken from our side. Should I have to take some bail in advance and will I be able to??