@tentosix YANBU. On these threads about vet bills, you will always get a few people on here telling you that vets should be allowed to charge what they like, as it's 'specialist care' that they have worked SO hard for, and you have all the nurses, the specialist equipment and drugs, and the electricity to pay for, along with the premises, yada yada, yada.
And the predictable comparison with the NHS comes along too. EVERY time... It's boring.
@willstarttomorrow
We also have a moggy who adopted us and is not insured. We love her to bits but she was pretty elderly when she came to us and has already had several happy years. When it comes to it we will have to make the choice to let her go.
I grew up with animals and vets have become more expensive and some of this is driven by insurance. I question whether it is sometime right to put an animal through complex treatment, although I understand why people do. Most employed vets earn very little although partners and get chains make a tidy profit.
This. Vet bills are^ extortionate at some vets, and they should be ashamed of themselves for charging so much. As the above poster said, vets have got WAY more expensive - especially over this past 20-25 years or so. And it does make you wonder if it's because they assume the insurance will pick up the bill! Although, as someone said earlier, the insurance companies often don't pay out in full!!!
Everyone I knew when I was a child/teen (30+ years ago,) had a dog or a cat, (me and my family included,) and I don't remember ANYONE getting a bill they couldn't afford to pay.
Yet these days, I rarely meet anyone who hasn't had an extortionate vet bill over this past 10 years or so. In some cases it has put them into debt, and has taken them as much as five years to pay it all off.
Just last January, my friend's dog got hit by a car, and had some bones broken, and the bill for the treatment came to £13,000! For a few hours treatment and mending a few bones! £13.000! The pet insurance wasn't worth the paper it was written on either, as the maximum claim in a 12 month period was £3,500. (It said it in the tiniest, finest smallprint, that you would need a microscope to read!)
I also have a friend whose dog had some dental treatment back in August last year. It cost £3,100! (It was not covered by the pet insurance conveniently.) The dog had to have a few teeth out, and had his gums cleaned and some plaque removed, and had some antibiotics, but that's it. My friend said 'this WILL cure the issue won't it?' The vet said 'of course.'
2 months later, the issue recurred. She took her dog back in, and they checked him over, (this took 5 minutes,) and gave him some meds, and gave her (another) bill - of £200! She said 'but should this not be covered, as I paid £3,000 for the treatment/removal of some teeth, that should have cured this?!' The vet said 'oh no there's no guarantee it won't come back!' 
She said she wishes she had got it in writing (from the vet) that the problem won't recur. And last week, the problem seemed to be recurring again! So that will probably be another £200 if she takes her dog to the vet again. For a 5 minute check up and a bottle of antibiotics!.
Seriously, do these vets think that if someone has a pet, that they have an endless supply of money?! 
As I said, I don't remember a SINGLE PERSON having a vet bill they couldn't afford to pay when I was a child teen (30+ years ago.) I don't remember anyone getting a vet bill of more than a couple of hundred pounds.
I remember my aunt's friend having a dog who needed treatment after falling awkwardly off a 4 foot high wall. A few broken bones, some meds and a few hours treatment, and an overnight stay. It cost her £185 in 1980.
Today's equivalent price would be around £950. NOT £13,000 like my friend had to pay (as I mentioned earlier in the thread.) And the treatment was very similar. The dogs were the roughly same size dog too.
Problem is with vet fees, they are limitless. They can charge what they like, and there is fuck all you can do about it. You are powerless. At this rate, no-one will be having pets - ever, and there will be 100s of 1000s of unwanted animals/pets.
Someone (in power) needs to step in, and start regulating the Veterinary Profession. Some of them seriously need investigating. And so do the insurance companies who rarely pay out when people try to claim, unless the figure is in the low hundreds. There is always something in the small print that means they get out of paying out on claims, as much as possible. As has been said, many pet insurance policies are 'capped' so they often end up only paying a small portion of the bill. Sometimes barely a quarter.
Also as has been said, when a pet hits 8-9 years old, the insurance goes up SO high, that it's unaffordable for many. As much as £70-£80 a MONTH for one cat in some cases. I don't know why they do this. It's infuriating.
I think the prices are outrageous, and many people I have spoken to have said they will never have any more pets after their current ones die, PURELY because of the ludicrously high cost of vet bills these days. As I said, someone needs to step in and stop them charging such exorbitant fees... I can't believe anyone has the audacity to defend them to be honest. And as has been said, many of the pet insurance policies aren't worth the paper they are written on!