If you have a contract for a service, quite often simply stopping paying does not end the contract - it just builds up charges and past-due fees. If you stop paying your electricity bill, the utility doesn't cut you off immediately - they keep providing service (availability of electricity, even if you're not using any because you flipped the circuit breakers) and charges keep accruing.
Eventually services will be cut off, but contractually you're likely responsible for charges up to that point and the companies involved may end up selling that debt to collection agencies (often for pennies on the dollar).
For utilities, you always pay much later after it was consumed. At least a whole month usually. It's a fundamental constraint with distributing water and electricity. You're always in debt with the utility provider.
For a newspapers subscription, you always pay in advance. They can cut it anytime. There is no reason for them to give you access if you didn't pay.
In the UK the utilities take money to meet an estimated bill; meaning most people are usually creditors to the utility. If a customer doesn't rein it in then the utility will often take stupid amounts to meet an anticipated bill.
I think they were threatened with regulation and so stopped being so blatant, but they make money off holding customer's cash.
The projection is roughly the monthly consumption from last year if I am not not mistaking. You should change provider if you're being charged stupid amounts.
The provider certainly allows debt when moving in, while the contracts and payments are setup. Afterwards, I am not sure if the last bill if for the next or past period, probably a bit of both.
Eventually services will be cut off, but contractually you're likely responsible for charges up to that point and the companies involved may end up selling that debt to collection agencies (often for pennies on the dollar).