Transmission started slipping after oil change - anyone else had this?

[thelmapye]

I'm honestly feeling pretty gutted right now and I'm hoping someone here can give me some advice or at least tell me I'm not alone in this situation. I've got a 2014 Q5 2.0 TDI that was driving absolutely perfectly before I decided to be a responsible owner and get the transmission fluid changed at around 90,000 kms. I took it to a garage that came recommended by a friend, they seemed professional enough, they used what they said was the correct fluid and they showed me the old stuff which was dark and definitely needed changing. But ever since I picked the car up, the transmission has been behaving really strangely, it's like it's slipping between gears when accelerating gently, almost like a momentary loss of drive before it catches again. Sometimes it also feels like it's changing gears too early and lugging the engine, which it never did before. I've taken it back to the garage twice and they've checked the fluid level and said everything is fine, but clearly something isn't right because the car was flawless before and now it's not. I've been doing a ton of reading online trying to figure out what might have gone wrong and I found some really detailed technical information at https://auditransmissionrepair.ae/audi-transmission-oil-change/ that explained the importance of the adaptation reset procedure after a fluid change, which I'm not sure the garage actually did. I'm wondering if that could be the issue, or if they used the wrong spec fluid, or if maybe they didn't fill it to the correct level when it was at the right temperature. Has anyone else experienced transmission issues immediately after a fluid change and managed to get it sorted out? I'm really worried I've damaged something and I don't know what to do next. Should I take it to a different specialist for a second opinion or just trust that the original garage knows what they're doing? Any advice would be massively appreciated because I'm genuinely stressing about this.