Company not giving resignation forcing not leave job how take action

I working for company in bangalore. Company sent me for onsite assignment in germany (April 2016) with work permit. For the issue of work permit they provided me a german work contract from my company in germany. While coming to onsite, i have signed the service aggrement which says that i will serve the notice period of 1 year after returning from onsite. Now i have received the better offer in german company and gave my resignation to current company. As per my german contract, i have to serve the notice period of 2 months. Now company is not accepting my resignation and asking me to come back to india and serve the notice period as per service aggrement or withdraw my resignation. Also they are not providing me a copy of service aggrement or onsite closer letter. Is there any chance that company can legal action on me? They have not spent any money on my training except flight tickets. Is there any chance i can take legal action against them by remain in germany?