Worst one i had was organising a 3 phase supply move in a occupied house divided into 3 flats + landlords supply. Each one with a different supplier !!!, i phoned and emailed all concerned twice each as i know how they loose info. On the day EDF turned up at 8.15am and cut off old supply and fitted new one. 10am EDF meter fixer turned up to connect the new landlords supply. 11.00am Scottish & Southern meter fixer turned up to reconnect 1 flat.
Then at 3.00pm (3 hrs late) British Gas meter fixer turns up and refuses to reconnect 2nd flat as its now PME and previously TNS. All earthing and bonding was run separately for all 4 supplies but the two ground floor flats had an additional existing 16mm earth running from their switch-fuses adj to the meter to the consumer units, joined at both ends( i guess the sparky at the time added this to back up the CPC's in the 16mm twin & earth. I claimed the DNO'S responsibility (re PME) ends at the switch-fuse's. I said i would remove the connection from the other flat then, but he said 'you will only reconnect it once i am gone'. As we were arguing a Seimens meter fixer turned up to connect the last flat, he listened for a while and mouthed to me behind the BG idiot 'ill come back later'. The BG idiot went on to say the other meter fixers were wrong to connect and he was going to report them, he then wrote out a refusal card and told me how to re-book a visit. He left & the Seimens guy who must have been waiting down the road walked back in, had a quick look and agreed with me all was correct. He connected the last flat.
I had to cobble together some temporary links to connect the BG flat to the landlords supply & that's how i left it, telling the developer it was his problem. The only tests any did, was plugging a Martindale tester into a socket for polarity. The BG guy asked to see certs for all 4 flats and even commented two done by a NAPIT guy were no good as they had to be NICEIC (these were the 2 existing ground floor flats)