Reliance Jio Infocomm — Demand for double payment and threading phone calls

Jio Fiber has not provided the promised service.
I paid complete 3 months in advance in Feb (Feb to end of May)
They are asking me to pay again for the period of April 21st to May 20th.
They are refusing to cancel the connection, rescheduling multiple times to collect their box without informing.
They are threatening with phone calls continuously resulting in disturbing my ability to work and causing mental agony.
They’ve also not provided the free voucher for 4th month.
I’ve sent an email to you as well dated June 4th.
Please take necessary action against them for the fraudulent activities they are engaged in - both service wise and accounts wise.