My company is breaching the employee bond

I have signed a bond agreement with my company in 2018 to provide me 100% fees for my degree program and duty hours adjustment and in replace i will be bond to be in your organization for 5 years (till October 2023). They agreed and started paying fees semester wise in bank cheques. In second year university revised the fee but my company paid me the semester same as it was in first year. On last semester they paid me half fees and directed me to pay the rest of fee on your own and we will pay you back when you show us the paid slip. I followed the direction and paid the fees. But now they are asking me we will not pay you the arrears until you complete your dissertation. I have cleared my 4 semester course work 1 year back and my dissertation is about to complete in 2 to 3 months. There was not any point mentioned in agreement about the dissertation. They didn't provided me the copy of agreement bond. Now my questions are 1. Now can i contact a court to get help me to clear my arrears ? or I should wait for dissertation completion and upon completion if they refuse to pay then i can contact the court ? 2. What are the consequences (if i resign now or after the dissertation, by making a point you have breach the agreement by holding my arrears), can they hold my gratuity ? 3. What are the possible option available for me to do according to your expert opinion ?