Always good advice to keep an ear to the ground.
Often a company will keep you updated or offer an opt out as often the info is often no interest, I know I do that by default with all the companies I deal with but it does mean that I have to regularly check to make sure I am getting the best deal.
If a package gets replaced sometimes a legacy product may be better for you than the new if the company is prepared to let you stay on it. You do need to check the terms and conditions because new stuff is not automatically better for you.
In reply to:
I just wanted to pass on this advice because from time to time we see angry or upset customers on here who didn't undertake this exercise and PN have been happy to continue charging them high prices for existing products when there were newer, cheaper, but otherwise broadly compaable products available which the user wasn't made aware of.
Tell me about it.

My building society has a new ISA account giving more interest, and all I need to do is switch accounts.

My fault I reckon, looking after my money is ultimately my responsibility.
Only a small responsibility I may add as it is only a small amount of money.