Is the service agreement bond legal if it is prepared on company letterhead?

I am undergoing a medical treatment of eye infection with specialist and since the covid case are reducing company has started to call the employees for office so I had requested my Team Lead to allow 3-4 weeks of extention wherein he was very rude to me in discussion so I had put the resignation. 1.When I put resignation email, as per company policy notice period is 90 days, however I requested to squeeze notice period so that I can find another job so company has reduced my notice period drastically and now I am getting relived from organization in just 15 days which was unexpected so now I will not get salary for 3 months and I do not have any other job on hand now and present company on top of that asking for bond amount which is 2 salary and 5% of CTC which is very huge amount so should this legal as I am leaving because of that mental harrasment of Team Lead and now they are asking for bond money. 2 I requested them that I do not have any job on hand nor I will get salary for 3 months as they are releaving me early so I do not have that much money to pay so company stated that they will hold my current month salary if I don't pay bond amount so is it legal to hold salary to recover bond money? 3.They have taken my Degree certificate at the time of joining as a security for 15 months that for 15 months I have to server bond and post that they will return my Certificate but as I am leaving early and not able to pay bond so should they also hold my Degree certificate? 4.When I signed the bond with company then at that time I only signed but there was no signature of CEO or any official.person from company so I have that copy with me where only my signature is there in agreement but not of Managing director or CEO where there was a place for them to sign but I was not given that updated copy having their signature too so what is the legality in this scenario? Is this agreement considered to be legal if it been written and signed on company letterhead and not using Government official stamp paper to use while preparing service agreement.