Looking on the internet deeply has found these results:

Awaiting for your prompt response. is the most popular phrase on the web.

awaiting for your prompt reply 15,280 results on the web	Awaiting for your prompt response. 130,100 results on the web More popular!
Some examples and use cases from the internet:	Some examples and use cases from the internet:
Just this once I thank you, Mrs Bonino and Mr van den Broek, for your prompt intervention. I would like to thank Baroness Ashton for her prompt reply and her reassurance two weeks ago that the matter will be treated on the highest possible level in the EU. Secondly, Parliament's proposal on the matter received a prompt reply. Mother, I pray for your health and for your prompt recovery. And she's promised A prompt reply. As 1 July is imminent, a prompt reply would be much appreciated. "For your prompt and professional service,"I offer my sincere thanks. Thank you for your prompt attention to this matter.	It doesn't look like this phrase is very popular! The search could not find any examples on the internet.

awaiting for your prompt reply

15,280 results on the web

Awaiting for your prompt response.

130,100 results on the web

More popular!

Just this once I thank you, Mrs Bonino and Mr van den Broek, for your prompt intervention.
I would like to thank Baroness Ashton for her prompt reply and her reassurance two weeks ago that the matter will be treated on the highest possible level in the EU.
Secondly, Parliament's proposal on the matter received a prompt reply.
Mother, I pray for your health and for your prompt recovery.
And she's promised A prompt reply.
As 1 July is imminent, a prompt reply would be much appreciated.
"For your prompt and professional service,"I offer my sincere thanks.
Thank you for your prompt attention to this matter.

It doesn't look like this phrase is very popular! The search could not find any examples on the internet.