How to pre-process the name String of a customer?
You may want to tokenize the strings, e.g., “Mustermann GmbH” tokenizes into "Mustermann" and "GmbH". Allow for spaces and commas certainly, perhaps also hyphens and other punctuation.

You may want to look into Natural Language Processing (NLP) if you're classifying text, but whatever method you choose should have better luck sniffing out business vs. non-business using tokens of the strings.