They are charging my long cancelled account

I canceled my account before moving out. And when I did I asked the agent I was speaking with what is going to happen to the router and ONT. I was told to leave it inside the house. So I did. I moved out on April 8th, with my subscription for the month still active, left the router there by the connection point not being plugged because I took all my twin plugs. Someone else had moved in on the first of May. In August Accelerit started contacting me asking about the router, I told them I did what I was asked to do. Then they went on asking me for the number of the body corporate which I don't have. I told them that I don't and they are the only operator in the complex they should all those details. How did they even get there in the first place.

Now they have decided to charge me for that, I woke up with a failed credit card transaction. I logged in into their online portal I see an invoice saying router replacement.

1st of all, you guys know that I have never used that router. I signed up for a 100mbps line and I was sent a router with a 802.11g meaning it can only do wifi up to 54mbps plus they don't provide the password for the interface. So I had to use my own router and we used theirs only when troubleshooting.

That router wouldn't be of no value to me, I have a lot of routers in my house that I don't even use. I am on a 1gbps with my current provider that I needed to upgrade to a high end mesh.

So you guys have a week to fix this and delete my card from the system or else it will be considered a "Casus Belli".

I WILL TAKE THINGS INTO MY OWN HANDS AND TAKE YOUR COMPANY DOWN NOBODY WILL EVER HEAR OF YOU AGAIN.