As others note, using one of the claims services is a waste of your money. As you have seen, the claims service did nothing for you that you could not have done.
I agree with you. I see two major problems with these claim agencies.
1) They only accept cases from passengers which are crystal clear. There are not the ones who try out a new legal ground. On the contrary, these agencies sometimes using the same arguments like the airlines to deny accepting your claim.
2) They have no teeth. In one example one claim agencies sued an airline right before statute of limitations kicked in (between filing the case and the initiation of the lawsuit, we had to wait 3.5 years).
Well I think that such claims can be enforced through the German and UK court system.
Thus, if a UK or German court gets jurisdiction, the airline are much quicker to throw in the towel. But when it comes to other jurisdictions (e.g. Finland) the airline simply ignore the letters from these claim agencies, knowing full well that these agencies won't invest thousands of Euros to bring forward a lawsuit.
Therefore, in Germany and UK it is more advisable to hire your own lawyer. In Finland it is advisable to not pusing it (and hoping one day you can take revenge against the airline).