Fini Technology — harassed by the company to pay more

I have taken the work from home project and as per the given time, i have completed the job. Latter came to know from their lawyer that their was errors in accuracy and fine of rs.10, 000/- has to be paid. Which i paid.
Again the same person mailed me and said that your agreement with fini company was 11 months agreement and i need to pay rs. 15, 000/- to them again and then the file case will be closed.