Symphony Limited — Symphony Air cooler Pump issue

Address: J P Nagar Bangalore (Bought from CROMA J P Nagar)

The issue raised with symphony on March 2020 and till now the problem is not resolved.
Service engineer is not responding and cheated me. I have paid 1200 Rs, he did not provided the bill and now he is not replacing the pump.
1. Air cooler pump was making noise.
2. At the first visit, the service engineer has replaced with a bigger sized pump. I paid him 400 Rs service charge and 900 Rs for the pump. Later i noticed that the water was coming out of the cooler.
3. After several follow ups, he came and replaced with my old pump. He told me that the pump is out of stock and will replace once i receive it.
4. Even after several follow ups the service engineer is not responding.
Please suggest and support how to get this resolved.