Hi,
This can be a tricky one sometimes, but it really depends on what sort of action you need them to take. I would avoid using 'For your Information' as this usually means that you do not expect them to take any action, just read it.
Without knowing the required action it is hard to be precise but you could try something along the lines of
We/I hope to hear from you soon regarding....
We/I hope you will be able to take appropriate action and would appreciate it if you could keep us informed of progress...
If you need any further assistance dealing with this matter please do not hesitate to contact me, and I hope everything can be resolved satisfactorily.
I look forward to your response....
Would you please let me know the date on which you anticipate contacting/whatever action......