So you've tried everything at your end to contact the company and it hasn't worked. The company is either ignoring you or they refuse to fix their product even though it's not working. The next step would be to send them a legal notice. This is a mandatory step before filing a case and serves as a warning to the company that you will escalate it to the Consumer Redressal Forum if they continue to ignore you.
You can contact any lawyer to get your legal notice drafted, ideally they should be someone who has some experience with the consumer forums. In this particular case, I didn't have any legal contacts so I used Voxya, an online consumer complaints forum, to get the legal notice drafted. I took up the ~Rs.2,000 package which included the legal notice plus the case papers for submitting to the Consumer Redressal Forum.
The information I collected in the last step was extremely helpful here. I sent all the evidence to the professional lawyer and they drafted the necessary documentation. In addition to the evidence, I also found the registered address of the company to send the legal notice to. The legal notice is sent by registered post so you get a confirmation once they receive the notice. The registered address can be found on the company's website or on mca.gov.in.
Once the lawyer gets confirmation of the receipt of the legal notice, there is a waiting period of 30 days within which the company needs to respond to the notice. In my case, we waited for 45 days and since there was still no response, the same lawyer started preparing the case documents.