> recently decided to chew out my phone lines from the wall (4 times now)
For her safety, and your peace of mind, she should be left where she cannot access items like this. You must be very patient to have let his happen a 2nd time let alone 3rd and 4th! :)
My neighbours dog has the run of their house whilst they are out and it has made her a rather anxious dog. It's almost as if she thinks she has been left in charge and needs to defend her territory, she worries about each passing walker or car door noise. I often hear her barking and I can see her running between every window to guard her house.
It may be the age of your dog that has caused a change or perhaps something new that is happening whilst you are out, but either way it makes sense to restrict her movements in the house and perhaps her view too. Many dogs will just sleep when their owners are out so the notion of being put to bed (perhaps back in her crate) is a good one. That may depend on your timings though - is 4 hours the norm?
If your dog has developed a desire to chew perhaps you could get her a kong or something that may appease her or if it's simple boredom could someone come in and let her out for you? At 12 months old you may well be noticing that she simply doesn't need as much sleep as she used to and she might need a small step up in her exercise regime. Good luck with whatever you try :)