When someone has done some task that you have requested and they have done it particularly quickly then this is the correct way to say thanks:

早急なご対応ありがとうございます。

さっきゅうな　たいおう　ありがとうございます。

sakkyuna taiou arigatougozaimasu.

“Thank you for dealing with the matter so quickly.”

対応

たいおう

“taiou” is used a lot in my office - whenever someone “does” something its called “対応”.

I think this means “taking care of” or “handling” a task.

早急な

さっきゅう

sakkyu

This means “very quickly” - both kanjis mean “fast” as far as I can tell. The second one “急” is used for the “急行” きゅうこう ( express ) trains.

This one has got me many times..

影響範囲

えいきょうはんい

eiqyou hani

( spoken as “eiqyou hai - in” )

It literally means “the range of effect” and is used a lot when we are going to make a fix to a program or do some other engineering task, everyone wants to know what parts of the service the fix or the work will effect - ( 影響　えいきょう ) and what the scope of that effect will be - its 範囲　はんい )

I heat this all the time and tried to look it up but couldn’t find it anywhere. The reason is they say the second word like “hai-iin” but its spelt “hanni” for some reason.  It is similar to 原因　げんいん which means “cause” and is said “gay-in” but spelt “genninn”.