Big issue with contractor on first flip. Can you help offer opinion for this situation?

[Chelsy C]

I am 3 month into my first flip. I encounter many issues.

Now, another issue. one of my independent contractor claimed that his workers get robbed at the property during rehab, and asked me paying back their lost which is about $700 cash. Also he claimed he has done much more than the contract state and spent much more time. He is demanding extra $1000 for it or he will fill a lien against the property.

I hope you can offer some help on this situation?