Byjus - Product cancellation

With due respect
I Sayeed Anwar Resident of Rz ****/**b, Tuglakabad extension wants to state that I have enrolled my Nephew Ehsaan Khan Class *rd in Byjus Tablet learning program costing Rs **k and had paid the Downpayment of Rs **k.
And got the Tablet and plus study course with it.
But as my nephew started using the same, he has shown no interest plus his school classes also started as I was also troubling through some financial situations, I decided to cancel the Product purchased from the BYJUS.
So I called my Mentor assigned to cancel the Product he also said that I would be cancelled and we have to return the tab back to Byjus.
But I got no back confirmation from them.
And soon I started getting the calls from the BYJUS to Pay the rest EMI for the product i.e of Rs **** but I also already told them to cancel the same and take the tab back.
But yet they are continuously calling and forcing me to pay the EMI , I am already in the worst financial situations and could not afford it.
Yet the EMI and not getting cancelled and I'm getting threating calls from BYJUS again and again.
Please see to it and help me to tackle it out.

Yours faithfully
Name Sayeed Anwar
Mobile **********, **********