Want to send notice to Hospital

Hi All, I took my mother to a renowned hospital in Delhi around 10-12 days back in emergency condition. It was Friday night. They admitted her to ward (not ICU) and gave me an estimate of around 1.25 lakhs on Saturday morning itself. The estimate was for antibiotic treatment for 5 days. The treatment actually required drainage from the liver which was not taken into account that time. On Saturday, there was no proper visit by any doctor. However, on Saturday morning itself, hospital tests showed that she was having severe infection which could be life threatening. Looks like no one observed those tests and senior Doctor came on Sunday and found out that my mother was serious and shifted her to ICU. The real treatment apart from antibiotics (drainage) started only on Monday and her stay got increased. We never got call from doctors or staff on how long the stay has increased and how much the estimate has increased. I myself approached hospital finance after 4-5 days on why they didn't give a new estimate. They apologised and gave a new estimate of 3.5 lacs. I was not in a condition to say 'No' to this estimate as my mother was in ICU. Since then, doctors have not been responding properly, but increasing the stay of my mother. There was no doctor to reply to my queries on weekend and 2nd October, but we are still charged for those days. Looks like these guys are giving fine treatment but taking things easy and slow. They had asked my insurance limit in the starting itself which was 5 lakhs. Now, they have given the new estimate of 4.5 lakhs. And all this, with the very same disease we went with and no surgery. I have not signed the new estimate for now. I want to consult some advocate before doing so. I have also taken all the clinical records (I had to fight for them) which show that there was no proper doctor visit on Saturday (the next day when she was admitted). Moreover, I made sure to record all the audio conversations I had with doctors and ICU staff in my mobile. Please suggest me what to do next. These guys are running pure business and trying to loot us when they can. I need help to sue them and want quick advice before they force me to sign the new estimate.