I have been on the "same" ISP every since I got ADSL in 2001.
I was with Griffin Internet, which got sold to Eurotel, and then to Daisy.
Everything was fine, with no problems about bandwidth consumption or reliability until I got loads of CRC and FEC errors for several months during the summer last year.
After logging a call they "fixed" it by dropping the speed from 11mb back down to 8mb (which was the max a few years before).
Anyway, things got worse when in November I got a bill for >£300, which included a charge for "data overusage".
When I complained, they said that they had turned on their data caps.
I said... ok, what is my data cap, and they said "2GB".
I replied "So I'm paying £70/month for 2GB.... seriously???"
After a long silence they tried to explain that there should always have been a cap but they had only just turned it on after the takeover from Eurotel a few years ago. They still didn't seem to get that paying £70/month for only 2gb was a little on the pricey side.
I was told that my only choice was to accept the new terms, or move to a new contract (12 months minimum).
I thought that in that case I would see if I could get some extra services, so I asked if they could provide IPv6 and to check that I could keep my static IPs.
Someone rang back to say that there was no guarantee that I would keep my current static addresses, and yes, I "could have 6 IP addresses".
After explaining the difference between "6 IP addresses" and "IPv6" and another long pause, they said they couldn't provide this.
By this point, I had got a bill in December for >£500, so I cancelled my DD before it could go out - the £300 had already gone out for the previous month, with no refund.
Aaanyway, at this point, I thought I might as well move to a new ISP as it was pointless staying with Daisy.
I found a post on this site for a company called Fluidata, which I have moved to, as they provide IPv6 and don't seem to have a bandwidth cap.
Even though I moved in mid February, Daisy still have not sorted out my account (29th March). They have refunded my over payment as a "good will gesture", (a laughable phrase - it should never have been applied in the first place), and any attempts by them to find my contract to prove I should be charged for >2gb (which they couldn't, and have never seen one since I received a very short one from Griffin Internet) have failed.
So far so good with Fluidata (although they don't seem to have many IPv6 customers, judging by the 3 weeks extra it took to configure IPv6 and lack of working IPv6 DNS servers), and although this is the same line as with Daisy, my speed seems to have increased back to the previous level without any noticeable errors.
The only thing now is to get fibre from BT.
This was originally "31st December" (a surprising date), then "January - February", then "January - March", then "February - March" and now "July - December"..... [censored]!?!!
We only live <1 mile away from the main exchange in a city of > 240,000 people...