I have been observing this thread for a little while, this type of problem with ISP's isnt as common anymore as it used to be.
My feeling is an outsider, I think they should implement some type of emergency traffic management at peak times as a short term measure, I would consider that better compared to indiscriminate congestion.
Should be an announcement as to whats going on other than support bods saying vague comments. The 2am and 2pm thing strikes as some kind of maintenance task that is somehow affecting their network rather than a capacity thing, and any ISP really should have automatic monitoring tools in place to pick up this kind of thing without needing customers to ring in and complain.
I suppose if they either dont know whats wrong, or projected fixes are not quick they might think it better to keep customers in the dark, but if I was a customer, with this lack of communication I would be looking to get out of my contract.
Meanwhile i remember my days on entanet many many years ago where they had a publicly disclosed traffic management system called STM (anyone else remember this?), were open with their customers, and I stayed on the ISP.