I have an E39 540i and it had the classic problem of dead pixels on the lcd. I had a go at fixing it myself with a pixelfix cable but unfortunately couldn't get the lcd to work at all after going through the process, and I had also somehow damaged the speedo and fuel gauges too.
So I sent it off to Cluster Repair UK, they said it was fixed and charged me £196.80. I needed it back urgently by the weekend so I also paid £80 for a black cab taxi up to their premises to pick it up. Eventually got home, plugged it in and discovered there were still dead pixels on the mileage counter. Bit disappointing but hey mistakes happen, so I sent them a screenshot but by then they were closed for the weekend. Driving the car over the weekend I discovered the speedo was also significantly less accurate than it had been before the repair. Before it was overreading by about 1-2mph, now it was over by 5mph at 30mph which is quite a difference, plus as you go faster the gap gets wider.
So I reported all of this to them via their web form, explained that the unit had already been worked on and that I didn't expect to have to pay anything for them to put it right as it should have already been fixed. On Monday I got a call from one of their technicians who was very aggressive and rude on the phone to me. He said things like "oh so you're the expert now are you" and was trying to suggest that I was talking rubbish and that I know better than their technicians. All I had said in my message to them was that there were still dead pixels and the speedo was inaccurate. He said "your speedo is perfect", and talked at length about how they calibrate them together with all of the other gauges and was seemingly refusing to accept that it could be faulty. He blamed the dead pixels on my cracking of the white plastic holder during my botched repair attempt, and that it's a £22 part to replace which is fair enough but then if they knew that part was cracked why didn't they repair it when they had the unit? Eventually he agreed that I could send it back in and they'd look at it because he found it really weird that it would be faulty again so quickly when they provide a 2 year warranty on their work.
Yesterday they called to say it was fixed and that they were shipping it out. He said they melted the plastic on the cracked part in order to press it back together, and replaced the new speedo with another new speedo and calibrated it carefully.
I got the unit back today, with the same dead pixels and the same speedo inaccuracy. The speedo might be 1mph better than before but it's still reading 30 when I'm only doing 26 (tested with gps) so is definitely not as accurate as it used to be.
Overall quite a disappointing experience, I'm decided to cut my losses and just live with the dead pixels and try to find a company that can do mobile speedo calibration.