What ard wrote...
A brother in law of mine owns a tranny shop in North Jersey and does E70 trans weekly, fwiw. He is also a proponent of remanufactured units.
If you do hit a trans joint, find one that does BMWs regularly, (some shops shy away from the brand), and be prepared to arm wrestle over the level of 'coverage', as it varies from shop to shop and via 'price/cost' level.
My bro-in-law also reports that they have serious code reader equipment and dig into the codes and electronics in attempt to narrow down the faults vs just tossing in a new trans and 'connector pkg'. I'm a little dumb here, as I have dug into manual trans a few times when younger, but never an auto trans...my point is find a tranny joint that works on BMW/E53 & E70s with some regularity and see what they have to say, assuming you have a couple to pick from in Alberta, eh.
Ugly deal on a car that isn't exactly ancient or beat on...I really like my manual trans cars, 2 of 3, and my motorcycles.
GL, mD