The "Transmission Service Required" message indicates a fault condition is present, which is borne out by the symptoms you're experiencing. It is not a simple service light indicator affair to remind you to change filters and oil at the appropriate interval.
A quick search on this forum should reveal to you two things of relevance to your situation:
1) Whilst Volvo originally considered the gearboxes to be "sealed for life", and don't have a gearbox oil change listed as a standard service interval item, many people report that reasonably regular changes prolong the life and can resolve some "roughness". But you're way beyond some roughness / clunking. An oil change isn't going to fix this
2) The General Motors gearbox fitted to the T6 XC90 is notorious for premature failure in this application. (I personally know someone who owned one from new and had two gearboxes fail before 60k)
That's not to say that your situation is definitely unrecoverable but I'd suggest taking it to a Volvo specialist, franchised or otherwise, sooner rather than later. If you prefer, and you've access to Vida/Dice, or can entertain purchasing them, it's possible that it will provide useful additional info; maybe it's just possible that the issue is electrical/control related. Any module / comms issues should be apparent from a Vida DTC read.
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2007 XC90 V8 Sport
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