ーて置く???
 

I was going through my grammar book and came across this form. I am not sure if I actually understand the meaning of it, even tho I guess I might have gotten the main characteristics. The problem is that all the example are translated the same way they would be translated without 置く.
I was wondering if this form can be translated with "already"...I try to make an example to show you what is in my mind.

I with a friend of mine are getting ready for a trip to Italy to the town where my parents live. My friend worried about where we can go after landing I thought I can answer 私の親に電話をして置きました. Instead of what my book would translate it (I called my parents) I see this phrase as a "I already called my parents" meaning I have already called them and arranged everything.
Am I traveling too much with my fantasy or I am on the right track with this form?

Ok, since I got this thread open I will use it instead of opening a new one.
どういたしまして: I know what it means, but can't separate it to understand word by word what it means. I mean I figured out it uses the verb 致す, but on my dictionary it only gives different kind of examples that won't help me getting a translation...and yahoo dictionary is only in Japanese and I am not good enough to understand the explanation yet.
Thanx again.

question 1:
You can understand "~しておく" like as " ... and leave it".
"私の親に電話をして置きました" would be "I have called my parents and left everything to them".

question 2:
It is difficult question even for native Japanese to answer.

After some study, I found it is to diny other's opinion very very politely.
Becuase ありがとうございます is "you are so kind or generous that it is rare or no one can expect it" word by word, denying ありがとうございます can be a polite answer for it.

As my personal opinion, どういたしまして could be "how can (I)?"."how come!?" or just simply "why?".
Adding some other words like as "受け入れられましょうか", it would be "how can I accept it?!".
Do you accept these?

question 2:
どういたしまして ->
どう - how, what
致す - do. humble version of する
ます - polite auxiliary
て - sentence connector or as question mark
In my opinion, this means 'What have I done to deserve thanks?' like as Not at all , No thanks are necessary.
Though, this is a debatable phrase as RadioKid said.