Yeah they all do it (insurers, TV companies, internet, breakdown, energy, whatever)... jack the prices for existing customers (while telling them about the amazing customer loyalty discount they are getting) whilst discounting new business.
And yes, its the people who won't switch that are the cash cows.
Generally older people... who believe in old fashioned concepts like "loyalty is important" and "cash Is king".
Its annoying though without a doubt and makes me rage every time - even more so when after telling you that as an existing customer they are giving you "the best price", only to have them lower it when you phone them up.... and it still be more than a new customer.
I had a phone call with my old insurer that went like this
Me: "I've seen a cheaper quote, can you match it"
Insurer: "Sure, tell me which website you've seen it on and if its a legitimate quote, we will"
Me: "Its your own website when I ask for a new quote"
Insurer "Oh..."