Firstly - for anyone confused, Turners Diagnostics and Turner Engineering are very different companies, and this thread is nothing whatsoever to do with Turner Engineering, who are a class act.
I had an almost identical experience with Turners Diagnostics about two years ago. I had bought my D2 with an Alive map and, as they were (then) an Alive sub-contractor, I wanted to have the map analysed as I was far from impressed by the performance and wanted to see if a remap would make a difference. I arranged to bring it to them on a Tuesday morning (no time set). I set off pretty early and got there just before 0900, to be met by an irritable old man who told me I should have been there at 0800. When I pointed out that no time had been agreed he told me to feck off and never come back. So I did. I notice that they do not mention Alive on their website any more.
I complained to Alive, who apologised and arranged for me to visit them in Lincolnshire. However, whilst they seemed helpful, I ended up paying for a lot of very poor advice, which cost me even more to follow, and knowing what I have subsequently learnt about LRs, I have no intention of going back there either.
If anyone is interested, they told me that the lack of performance was due to a worn turbo. My Hawkeye was suggesting the the MAF throughput was fine and there was no obvious wear, but in deference to their advice I bought and fitted a hybrid CHRA. No change to performance or airflow figures, but searching on here I found what MAP reading I should be seeing and mine was far too low. The air was obviously going somewhere and it turned out the silicon hose from the intercooler to the inlet manifold was slightly too short and had come off. Longer hose fitted and power restored. - Yes I know I should have spotted that long before, but it was my first TD5 and I had a lot to learn.
I had just had a V8 torque converter fitted and there was a transmission thunk on slowing to a stop. They diagnosed a dying rear diff - even suggesting I might not make it home. I bought a replacement, swapped them over and had the old one tested - absolutely fine. The thunk went away when I forced the autobox to relearn the adaptations (which I should have done as soon as I had the TC swapped), now smooth as silk, and with power restored, a joy to drive. Paying for and following Alive's advice cost me around £850 and in itself would have achieved nothing; if I knew then what I know now (mainly thanks to this site), I could have fixed my problem for the cost of a new bespoke silicon pipe - £45.