Plus Net is expensive

[#1]

Which largely backs up the OP's assertion that loyalty doesn't pay.
Most that read my posts about discounts will already know that I disagree with the level of discounting / cashback seen at times for new customers (Plusnet being no worse than most others but they could actually be better than the others if they wanted), some previous deals can only work if subsidised by existing customers (or they get a high retention rate at the end of the offer period).

[#2]

I'm on a Market 1 exchange and got a 24 month u/l deal last July -when I added on ALR (which still included EVE/Weekend calls) and daytime calls via 18185 ,my overall costs comfortably beat the then Sky deal I'd been offered -so it CAN be done.
As to Insurance Cos., Utilities etc -I move everything every year (and in the case of utilities, more often for cash back deals) -now they are REALLY bad at retention deals !!!