RE: Battery hire?
Technically, you really have a bargain on your hands. It is the previous owners responsibility to ensure that the battery lease is transferred to the purchaser. If you were able to purchase without the 18 page battery terms, there is absolutely no need for you to do anything - indeed it is not even a liability for you to bother about - even retrospectively.
All this shows is how simple it is for a Fluence to be disengaged from its battery paperwork if the seller isn't vigilant. Indeed, as they are obliged to continue paying for the battery, RCI won't care either way!