FastWay Transmission — unethical behaviour

The set top box was working perfectly fine. One day the guy from the company came and took the box back and gave the old non-working box.
When we complained at the office they said you need pay 300 we need to repair the box. We paid 300 and there was nothing done.
After that when we visited the office, the owner of that office didn't show up.
We asked the agents to come and look. They said go and reach out to the office. We visited the office n number of times, but no one responded.

Today again we asked the agent to check our box, he did not responded. Ignored and went away