Byjus learning app - Illegally deducting Money after Cancellation

I had purchased Byjus class * to * product for my son from Mr. Aman (representative of Byju's) with a written commitment that if we don't like the product; we can go for cancellation within ** days of delivery, and Byjus would refund all amount in full. We got this Product delivered to us on Aug *, **** and found it of no use for my kid within the trial period; so asked them for cancellation on Aug **, ****. Instantly we started receiving calls from Byjus representatives Arushi and Shantnu, and finally after all discussion with me and my kid, they asked me to send mail for cancellation. The mail was sent to Byju's on Aug **, **** for Cancellation. Since then we have been waiting for their representative to collect the kit and refund the amount that was given at the time of purchase. But to the extent of my surprise, they commit that cancellation request was in progress and they keep deducting payments through ECS (that was asked to be filled at the time of purchase). When i asked to cancel the ECS and refund my money, they are refusing to refund my money back. I have requested many times to Shantanu (Byjus representative) to arrange a call with his senior then he said he is the only authority to respond back and he clearly told me to DO what ever I want to do, and money will not be refunded.
They have been calling just during trail period to kill time, so that ** days are passed and they need not to return the money. Since everything is in writing, and after the last request of cancellation, which they did not do; no one from Byjus called up for any service/status update.

After my bitter experience on call with Shantanu, I am forced to take required measures and thus writing here.

It is how a common man is being looted by such companies, they are sponsoring cricket matches from illicit retention of General Pubic hard earned money.

Transactional reference of product that was purchased from Byjus is as under. We have all artefacts to prove our stand, and expecting someone from authority would read this article and take required actions against Byjus.