Monthly plan charge.

Hi, I had a Basic plan for my Ring 2 and received a replacement for it because it was faulty. So sent it back to Amazon. I have deleted that Ring from my account a month ago. This week I was charged for the monthly subscription for the old device, the new device was still on a trial version. I thought the basic plan will just be added automatically to the new device. So yesterday it was last free day and as of today I need to pay for a monthly plan for a new device, but on 11/05/2020 my account was charged for monthly Ring plan. Don't understand how this works. To mention on my account is registered only one device. Thanks.