what should I say to thank for in this case?

[Anonymous]

I needed some information and somebody told me that he would ask somebody about it. It was kind of his duty and in the end, he couldn't get satisfactory results. But regardless of the results, I'd like to express my thanks to him. I don't know him well. He's a staff of an organisation. In this case,

Thank you for concerning me.
Thank you for your concerns.

Are these good for that?
Or if there are some other ways that are much better, please let me know!


Many thanks!

 

[beeja]

Thank you for your kindness.

or Many thanks!

 

[Francois]

Thank your for your help/the time you spent/your efforts.

FRC