Repair Shop Shenanigans?

Hi,

As the name states, unfortunately, I don't know much about cars other than how to drive one. I would like to ask for some help as to the information I've been given for a repair on my 2014 Subaru Forester. I'm searching to find out if this is at all possible, what the dealer is saying:

I brought the Forester it in to a dealer because I had 2 transmission error codes from a check engine light. The both referred to transmission. The dealer replaced the Transmission Body valve. 3 weeks later, I had a leak, brought it back to the dealer and they said it needed new Deferential seals. I agreed to the work. They replaced the seals, called back and said that someone else must have over torgued the transmission and cracked it and I need a new transmission. I mentioned that they worked on transmission last but they adamantly and said I probably brought it to a poor shop and when replacing the oil they unscrewed the wrong thing, realized it, and tightened the transmission screw(s) too much. Stupid question - is that mistake even possible? I don't know much about cars, but is the engine oil even near where you would drain the transmission fluid?

Thank you in advance.
John

Yes, some people have mistakenly drained the transmission instead of the oil, it seems to happen a lot to Subarus.