I had a similar, more bizarre, situation where the team I was leading was responsible for the user interface to a system and another team was building the database. I asked them to provide us the API for retrieving the information we needed to display and their team lead responded by saying that if we told them what we would ask they would tell us if it was right. So essentially we had to play a guessing game with them. In normal circumstances, I would have escalated the issue but the company was acquired and all but a very few people were laid off making the whole thing moot. (This was Sterling Software acquiring Texas Instruments Software and killing off Knowledge Craft).