Reliance Bigtv — big tv not installed even after 3 months

I prebooked Reliance big tv in April 2018 and even now it is not installed. My booking id is 14547248. They have the most unprofessional customer care service and never respond to the mail and calls. There is no point of having a customer care if they can’t satify the customers. Please refund my prebooking amount back to the amount it was originally transacted. If you can’t fulfill the demands, please don’t accept more orders and keep every customer waiting.
Worst experience.