The financing heavily strains your household. You wonder whether the bank adequately examined the economic situation at the time of signing. That can be a sensible professional assignment for review. A later difficult month, however, does not by itself mean that the creditworthiness assessment at the time was unlawful. What matters is a comprehensible factual situation as it existed then.
First distinguish between then and now
Create two short snapshots in time. The first should record the actual circumstances and information at the time the contract was concluded. The second should record the changes that occurred later. New unemployment, a subsequently increased expense or a burden already known at the time are different facts. What legal significance they have must be examined individually.
Gather the complete contract including amendments, the income and expense documents submitted at the time and any correspondence available. Record which information was transmitted to the bank when and what response you received. A reminder is to be labelled as a reminder, not after the fact converted into an allegedly then-sent proof.
The statute has effects and exceptions
§ 505d BGB regulates possible consequences of a breach of the obligation to assess creditworthiness, including a there-specified reduction of interest and a right to terminate without prepayment penalty. Paragraph 1 simultaneously contains a limitation where the contract could have been concluded following a proper assessment. Paragraph 3 excludes certain intentionally or grossly negligently incorrect or withheld information. [BGB505D]
A possible limitation of claims because of a later breach also requires, under paragraph 2, the connection described there with the circumstance that would have been decisive with a correct assessment. [BGB505D] For that reason the provision is not a general debt relief in cases of payment difficulties. This article neither confirms a bank breach nor a claim to a particular correction.
A hypothetical difference in the evidence
In the first invented case a then-regular expense was listed in an actually submitted piece of evidence. In the later personal copy of the household budget it is not recognisable. The person concerned submits both documents with dates for review. Whether this proves a relevant error remains open.
In the second case the additional expense arose only several years after the conclusion. It belongs to the current shortfall solution but, on its own, does not explain the information available at that time. Both cases need financial support in the present; only their historical starting points differ.
Take the payment issue seriously at the same time
An ongoing legal review does not by its mere existence halt actual due payments. Clarify with appropriate advice how you should respond to letters and payments. Do not unilaterally change instalments on the basis of this article.
The prepared assignment is concrete: Which information at the time was taken into account in what way, which statutory standard of assessment applied to this contract and what consequences could be considered after a full review? This turns an understandable concern into a verifiable question, without promising you a certain outcome.