Einburgerung #PassExperten

Hi everyone,
I applied for German citizenship (Einbürgerung) in Brandenburg/Cottbus a few months ago and recently I was contacted by a company called PassExperten. They are offering a fixed-price service for around 2000€ including:
Full support during the citizenship process
Communication with authorities
Untätigkeitsklage / speeding up the process
Objection/lawsuit if rejected
Lawyer and court costs included
They also mentioned they may help accelerate the process.
My situation:
Self-employed residence permit (§21 Abs. 2)
Around 7+ years in Germany
B1 certificate completed
Einbürgerungstest passed
Application already submitted
I wanted to ask:
Has anyone here used PassExperten or similar services?
Are these services trustworthy?
Can a lawyer actually speed up citizenship cases in Germany?
Is an Untätigkeitsklage really effective?
Is 2000€ reasonable for this type of service?
Has any self-employed person here successfully received citizenship or PR with lawyer assistance?
I would really appreciate honest experiences and suggestions. Thank you!