Regarding Relieving letter, Experience letter and FNF

Dear Sir/Madam, I am facing a great problem with my employer. When i join the so called company in 2016 as a Account Executive I demanded a 30% hike on my current salary, but the HR refused it and they told me that they will give 25% increment after one year, so i accepted it as i was not having any option on that time.But after 1.2 years when i asked for the increment they postponed by increment after six months.I was very sad by this news and started to look after a new job and luckily in one month I got the good job with goods hike. Now on 03rd July 2017 I have sent a resignation mail to my finance HOD and VP-HR that i am resigning from my Account Executive post and my last working day will be 17.07.2017 (i.e. 15 days) As per the company policy it was 30 days but while sending the e-mail i stated that I am ready to pay for the remaining 15 days to company.Yesterday when i had a talk with the HOD he told that you have to compulsory serve the notice period of 30 days or else we will not provide you the Reliving & Experience letter and also we will hold your two months salary which is approx Rs.40000/-. As my new employer is offering me only 15 days to join the company. Hence ,request you all to please help me out from this problem, 1. Can i file a case against the employer to clear my exit documents and FNF. 2. Is there any other option from which I can fear out the HOD and VP-HR which are the badest person on this earth. 3. Or I shoot the mail to my MD about all these things. Thanks Yogesh Kadam E-mail - [deleted]