Tikona — They are asking to Pay for the service I didn't used and also not refunding my taken by saying they will upgrade plans

Respected Sir/Madam,

Customer ID = [protected]
Name = Vishal Gupta
email = [protected]@gmail.com

I took 6 months Tikona internet connection on 28th March 2020.
While taking connection I told them I need a plan with speed of40+ mbps but they provided me plan of 10mbps as they don't have high speed device and assured me will upgrade my connection within a month. But after multiple complains they didn't upgraded my device.
Now after completion of my 6 months billing cycle I asked for discontinue of the services but they didn't showed up instead they sent me another 6 months bill. After complaining to them they told me it will not be a issue but they keep on sending bills and new package options instead of taking away their connection.
Now, on march 2021 I asked them to stop calling me and take your setup away but they insisted to try high speed packs with promise of good service. They asked me to pay ₹707 for 1 month 25mbps pack. I paid that online.
After 2 days when my connection still didn't resumed I called them again to which they replied that 25 mbps per month pack not available in my area.
Now when I asked them to refund my money which I paid they started to resist and tried selling me 10 mbps plan again which I denied and asked them to refund and take away your system but instead they again asked me to pay 6 month bill (sep 2020 - march 2021) for the service which I never used and also deducted my paid ₹707 in that bill.
Now they are asking me to pay around ₹4500. Threatening and harassing for legal action via calls. The caller stating herself as a lawyer which I doubt.
Kindly help me out from this fraudsters who are mentally harassing me.
Also, they have already not refunded my router money around ₹800 which was given to me giving wrong information by their ground staffs.