Hatway broadband internet services - Deficiency in provisioning of internet service

I have internet connection from Hathway broadband internet services in Surat having account no. **********. The plan name is GPON FREEDOM *** MBPS.at the time of purchase of the plan it was promised by sales executive that the internet speed will be *** mbps. But after installation and activation it is found that speed is not even ** mbps. On complaint to the service provider, the service engineer says that you will not get *** mbps. If one want *** mbps speed, one has to purchase a separate router costing around Rs ****-/. When told that the sales executive did not disclose that one has to Purchase separate router, he just transfer the blame to sales executive and sales executive blames technical team. There is no contact details are provided of any senior functionary and customer has to just bear this deficiency. This is highly unethical and clear deficiency in service.