Am I absconded?

I worked in a proprietorship firm for seven months, as per the appointment letter i supposed to be a confirmed staff in six months and will entitle for paid leave and other benefits, though they haven’t confirmed me after 6 months and i got the salary after all deduction including leave salary, they were also deducting a good amount from monthly salary as retention money, they never provided me any facilities or equipment to work after working hrs in spite of that they forced me to work on odd hrs/from home/weekly off and on holidays, which was highly difficult to manage in the lack of sources. I discussed the issues with MD of organization informing the problems I was facing from him and within the company that disturbing my family life and health, I told him that it will be difficult to serve them in this situations, but he haven’t acknowledged the issues and did nothing for improvement. Due to highly frustration and stress haven’t reported on job from the next day of last salary, and send them my resignation on email requesting to relive me with immediate effect. I was not given any company assets so there was nothing to handover, nevertheless all the work-related information and details whatever I was handling there I gave them in written, so any one can handle that easily. I haven’t ask for relieving letter or any FNF amount, also wrote in my resignation that they can call me if they need any work related assistance. After I left they have never called me on phone, but in few days they started to sending me notice on my postal address/mail address saying that as I haven’t served 60 day notice as per the appointment letter hence they declared me an absconded staff and they will take legal actions against me. Please advise what harm they can done to me.