Usys Services — demanding money

I applied in the above company for form filling job. Due to my illness i was not able to complete my work, so i asked for extension. They asked me to pay extension charges for which i don't have money to pay. I told them that i will complete the work and they can deduct from my salary but they didn't agree to it and asking me to face legal challenges. Later, i found it to be a fraud company trying to extract money from people citing one or other reason even if the work was completed properly. Pls help me out to deal with this people to resolve the issue