For an own campaign, keep the advertising version, approval record, cost matrix, product configuration and documented order journey in the same file. Add billing examples, technical changes, complaints and the response to any identified discrepancy.
For observed competitor advertising, preserve the complete advertisement, date, URL, visible qualifications and sequence of order steps. Isolated excerpts may create a different impression from the full campaign. Legal review must also establish who may bring a claim and which protective objective is appropriate.
The canonical German article on the UWG blacklist places all automatically prohibited consumer practices in context. This article remains limited to free advertising, unavoidable costs and mandatory additional charges.