Offtech Enterprises — not completing the work

I find tha job on quikr.
I completed my work in the time. But they are saying you are not completed the work, you should pay the money of rupess 9300/- for not completing the work. They said work will complete in the time. They are also blocked my number. I called so many times to the employee but there is no response and blocked my number.

I completed the work within the time. But they are harassing me. Please help me.