Not paid salary and bonus even though written in appt letter

I work with a small association in Ahmedabad having total 5 employees. It has PAN card under Association of Persons (AoP) category and is not a registered organisation. In my appointment letter my designation reads as Administrative Officer. It is mentioned in the Appointment letter that apart from salary, I will get a bonus as per the norms of the association. Bonus is paid during Diwali @ 20% of the salary to other employees. I joined the organization from 22nd August, 2015. And during Diwali 2015, I was not paid the bonus as I had not finished my 6 months. Thereafter on 30th March, 2016, I was told that the committee members have decided to discontinue my services and that I may leave the office premise. I asked for the salary of March 2016 and one months’ notice period salary for April 2016 and relieving letter. I was told that it will be given in April 2016. Having been convinced, I left the office premise. Thereafter I was called to the office on 11th April, 2016 and was asked to sign the resignation letter, which was prepared by the office on my behalf. They told me that upon signing the resignation letter only I will get the cheque for salary of March 2016 and Notice period amount for April 2016 and the relieving letter. I denied to sign any such resignation letter as I have no intent to resign from my services. Thereafter they did not pay me anything nor did they gave me relieving letter. Thereafter on 20th April, once again I requested for my salary of march 2016 through the email. In response to it the office wrote that I was already offered the salary and notice period amount upon signing the resignation letter. Now since I have denied, the office will pay me my salary for march 2016 and give me my relieving letter. Thereafter nothing turned up, hence I issued a legal notice to the office on 22nd April, 2016 through advocate to pay me my dues ie. 1. My salary for March 2016. 2. Notice period salary and 3. Bonus for the months from August 2015 to April 2016; and mentioning that if the said is not paid, I will file complaint u/s 406, 420, 114 of the IPC and a suit in the labout court to recover my dues. Replying to the notice the office agreed to pay the salary of March 2016 and denied the notice period salary saying that such fact is not mentioned in the appointment letter. Also mentioned that I cannot approach the labour court as my designation is Administrative Officer. They did not mention anything about the bonus in the reply, though it is mentioned in the appointment letter. Thereafter, cheque for salary of March 2016 and relieving letter dt. 21st April, 2016 was sent through RPAD from the office which I received on 27th April, 2016. Now my question is, whether I can file a written complaint u/s. 406, 420, 114 of the IPC for breach of trust etc. in the local police station? Please advice further, how to get back my dues from the organization? Whether through the labour court or through city civil court?