2013 a3 auto trans service

Dealer said it's a sealed unit and don't need it till 115,00 miles is this true I
was looking to spend the free $500 visa

If it is a DSG, it requires a service every 40k miles.

I have no idea what "sealed unit" means, as this seems to be thrown around a lot. It is no different than most other transmissions. It has seals, and it is full of fluid. It has a service procedure, which involves draining, refilling, and checking the level, same as any other transmission would. Just because it has no "dipstick" does not have anything to do with its service. LOTS of transmissions do not have a dipstick, and even some engines are not using them either.

Your owner's manual will have the PM schedule listed. Audi is a little different than Volkswagen, no idea why, but they have a 5k service, then a 15k, 25k, etc. Volkswagen has the first service at 10k, then every 10k thereafter.

Dsg service

Thanks just as I thought about 40,000 miles having it done next week