In reply to magma:
True story. I got a water bill. I was bit surprised as it's normally about £200 and this one was over £70,000. I wasn't worried, because it was so clearly an error.
I wandered out into the front garden and read the meter - sure enough it was massively different to the reading they supplied.
Things became less rosy and reassuring when I called them to straighten it out. I'll spare you the queueing and general difficulty in getting to a person. Bottom line was "The bill is based on reading by one of our meter readers; it is not possible for it to be incorrect". The person went on to helpfully advise I check for dripping taps or a leak somewhere. I pointed out that I could have every tap in the house running full pelt 24/7 and still use only a tiny fraction of the 50,000 m3 they were trying to charge me for 5 months' water. This cut no ice. No they couldn't take my reading. No they wouldn't send another reader out, they had a valid reading. No there wasn't an escalation route.
After a bit more to-ing and fro-ing I was advised to write a letter of complaint. This had to be done by post; e-mail or phone complaints aren't, apparently, complaints.
I wrote a letter explaining and sent a photo of the meter.
A while later I got a letter ... a red bill demand. I called again and asked that they put the chasing process on hold. Not possible. But they had my complaint and I should expect a response in a few weeks.
The final demand before legal action prompted me to call again. No, they had no record of a complaint, nor my previous calls. I explained the issue once more and resent the complaint recorded delivery. I also paid the correct amount based on the actual reading.
The next ~six months were spent writing roughly monthly. The legal threat developed into talk of a court date. I didn't dare look at my credit rating. My faith in common sense prevailing was getting eroded a bit.
Finally someone, presumably in their legal team, must have reviewed the file. They called me. I explained an nth time; a bit shirtily now. They wouldn't accept my reading or photo as "the sum is so large". But, in a breakthrough, we agreed they'd send a new reader out. I'll cut the fact that they didn't show up first time. The second time, my neighbour knocked on my door asking if I'd mislaid a meter reader chappie - who was very insistently wanting to read my neighbour's meter but asking neighbour to confirm his name as mine.
I showed the bloke my passport, my bill and my meter - in my front garden, not the neighbour's. He said, with surprise, that it explained why he couldn't match the serial number on the account.
I got a letter cancelling the legal action and a corrected bill. No apology, no recompense, no assistance with repairing credit rating...and, of course, no way of chosing an alternate supplier.
"Computer says no" is a very black witchcraft.