ACT Broadband - ACT Sent bills two months after Disconnection and I paid extra which is denied to refund

Background:
*- I opted for disconnection on sep ** , I got a phone call from ACT service team asking for a reason and got email confirmation for on sep **.. (attached the image of email)
for safer side , I disconnected the router and Ethernet cable as well.
*- I was getting bills and I kept paying for sep, oct, and november as well. I called customercare couple of times and on december the representative told that the money will not be refunded however we can adjust with any other ACT account ( friends or relative ). so i shared another account details (************) and I didnt see any money transferred to the new account.
I did followup on *-Jan-****, customer Care person says the money cannot be refunded or transferred to another account.
my request ,
*-after disconnection i paid * extra bills, i want my money to be refunded .
*- how to raise consumer complaint legally? I have bills and email confirmation from ACT as evidence.