Two weeks ago, both Haas cars were eliminated from the Silverstone race, which left Steiner exceptionally frustrated as it aimed to understand why it is struggling with its long run.
Grosjean was reverted back to the Australia-spec car for the weekend (which he will also run at Hockenheim), but the team was left with no information following the double retirement.
"I'm still not over it," Steiner said. "You've got a certain amount of opportunities and this year we are struggling in some of the races. The car on Friday was a lot better in long runs, and that is on times - if you compare them, it's factual.
"If it would have been the same in the race, 100% I can't say but the chances were high. Then we go out at Turn 5.
"Our position at the moment doesn't reflect where we are in reality. We've got these big ups and downs, and when we've got ups, we put ourselves down one way or another. That is quite frustrating.
"They need to understand where we are. They don't let me down as a person, they let the team down which is disappointing. Normally I get over things pretty quickly but this one, we had a clear talk after Barcelona what to do, what not to do."
Steiner added that there has not been any more progression with Rich Energy, who made headlines during the British Grand Prix weekend.
The company has since been renamed to Lightning Volt Ltd, with Steiner stating that it needs to get back to Haas before the summer break.
"We are still at the same point with Rich Energy, we need to hear from them," Steiner said. "I don't know what is going on internally. I don't want to and I don't need to.
"Between them there are investors, shareholders, I don't know what they are battling. I don't know, so I can't even speak about it. With us, they need to come back to us before the summer break.
"It's a legal deadline which is clear and we go with that one. I don't need any lawsuits, I've got enough going on.
"We are square to wherever we are. I'm not allowed to say any dates or details, we're okay at the moment."