Legal Advice/Help - Where to go? (Trier)

I have faced some problems, or just questions, about how the law works in Germany, specially when it comes to consumer rights. The problem is that I have no idea where to go for advice when I face these situations.

The last one was a charge on my phone bill for a service that I supposedly subscribed though my phone. They simply said that they have the records and that they would charge it. Period.

I also had another problem (a lot bigger) with Western Union almost one year ago and until now I couldn't make anything against them. I just lost the money for good, apparently.

Is there any department that regulates and/or supports consumer rights, where you can ask for advice or report actions against a given company?

Thanks in advance for any help.