Had the auto on my SD1 overhauled by a local company a couple of years ago. They were recommended by all I asked in the local trade. Made a fair job of the actual overhaul but not of the installation. Probably different fitters. When I got it back the exhaust was blowing. Being short of time I got the local Kwikfit to sort it - it's a stainless system so not rusted through but just needed new gaskets etc. Other issue was a leak from the box - but only when the car was parked on a slope.
The speedo has been intermittent for ages and I eventually sourced a new sender and got round to fitting it. It's a bit awkward to get to so means removing the exhaust downpipes and dropping the back of the power unit.
And guess what? The central large bolt on the gearbox mounting was rounded off. And tight as f**k. Out of the four 5/16ths UNF bolts holding the mounting bracket to the body, three had stripped threads. In the captive nuts of course to make things even worse. Other thing was the loom to the speedo and reverse light switch etc wasn't correctly routed and had frayed through the insulation. Must have been seconds away from a serious problem as there's no fuse on the speedo side.
The leak was from the selector shaft. No oil seal fitted. I'd changed this before and it had one when it went in. I'd also fitted a new rear mounting, and know everything was correct there before the gearbox was removed.
Of course it's too late to do anything now even if I could prove things - but it just confirms my belief that much of the garage trade is pure incompetent. It must have taken real effort to strip those threads as the inner bolts can only be reached by a 3/8 drive socket and would be difficult to exceed the correct torque with a 3/8 ratchet.