They don’t want to talk to you. Or anyone else. Unable to justify their actions. If they were a business they would go out of business. There is something you could do. Ask your bank/credit card company for a chargeback. They will contact Thai Embassy in Munich and ask for an explanation. If no response within 30 days you should get your money back. However, there is the possibility that doing so may count against you if/when reapplying.
We shall never know. Her sister got turned down for Australia and Netherlands (Schengen). However, when the Schengen Visa was resubmitted (with exactly the same details) it was granted. Government departments sure are arrogant as well as incompetent.