Full and final salary

Dear sir I have been working in retail and it's a since 9month. Before a month whether happy with performance or some internal politics I was taken out by my senior sudden death by doing audit. I have a shortage of 12k so which I was responsible. But I told them to deduct my shortage percentage and please enjoy your do my full and final because I'm only source of income of my family and I have 2 years old son. When I called them for my full and final they told it will take a week I waited for again calling second time some other excuse and calling continously for a month now there is more shortage that I have to pay. I told them when once audit is done in front of them, I was not present on store for a month how shortage comes on me they have been giving their explanation. At the end I told them deduct my whatever shortage but release my pending money my leave my bonus and whatever is left but I told them I need audit proof paper which was before leaving a store give. Now they are saying it's official paper they can't give. And they saying I will not get my leave money my bonus. Its company policy to deduct a paid leave and bonus. Please suggest me what to do. Shall I mail the higher people of the company or some thing else