Shop and move every year.
When I was working and too busy to pay proper attention to insurance and utilities, I stuck with the same company as the car aged and devalued, but the insurance only ever crept up. When I finally shopped around and moved, I SAVED over £400 a year on the same vehicle.
I've over paid thousands over the years because I was too busy to shop around.
Ever since, come the end of the year, they always try to jack their prices up. 20%+ is commonplace. I call them, tell them I'm willing to pay 5% more than the last year. Take it or I cancel....So far, no one has agreed so I cancel and move the policy. I always get a quality insurance policy for the price I'm willing to pay.
I've saved hundreds a year by shopping around for utilities too.
There's no reward for loyalty so there's absolutely no reason to give any loyalty.
Decide what the going rate is for a product of the right type and quality, then simply state "I want (this) and I'll pay you £x for it". Take it or leave it. I'll buy it somewhere else if you don't want the business. It takes all the hassle out of "negotiating". I've watched hard nosed negotiators at work in asia. This is their approach. It works for me.
If no one will deal, you know that your judgement of the market price is wrong