I would like to take a moment to stick up for "Baschti."
On the one hand, the "advisors" from Stadt & Land do indeed (more or less) offensively offer their customers the option to organize the financing for them. They also have a great comparison program at hand, which shows the customer that two banks would gladly finance him and one possibly would. The goal and background is, of course, to move customers who do not want or cannot deal with this faster to closing with this "service" ("look – the financing is already taken care of, so you can just sign").
Of course, we have all tried to get offers and compare them with each other. Some more, some less cleverly. I myself named the conditions of the competition to my preferred financier in the final phase so that he would come a little closer to my terms (by the way, this also works very well when buying a kitchen – although I did not mention the competitor’s name for the kitchen).
What I want to say with this – even if Baschti may have made a mistake, he was simply trying (possibly also trusting the advisor from Stadt & Land, who wants to arrange everything) to find a financing that suited him / was better – just like we all do.
Now – having realized what this "all-inclusive advisor" really is and how he acts, he has to draw the right conclusions and act accordingly. He has gotten the relevant tips here. If he does not act, he has to live with his decision (the construction partner and the financier).