Regarding payment dues for four months and ignorance after demanding my money

I had agreed to give home tuition to a girl for a monthly payment of Rs 3000. I taught her for about 15 months. During this period, her parents started making excuses, sometimes saying their son was unwell, sometimes saying they did not have salary, and kept promising to clear the dues next month along with the current payment. As a result, they have not paid me for 4 months, which amounts to Rs 12000. When I asked them for my payment, they started ignoring me. They blocked my phone number, and when I called from another number, they would cut the call as soon as they recognised my voice. I urgently need this money and have repeatedly requested them to pay, but they have still not given me my dues. I request that the concerned parents be directed to pay me the pending amount of Rs 12000 for the tuition services I provided.