I have heard people say: "I booked a room" when coming to the place they stay or "I have booked a room". "Have booked" seems to be more common though.
I don´t understand why. It should both work, shouldn´t it?
Also, when you say "I made a reservation." it seems that it is always used with the simple past.
The same is true of some verbs like "forgot" or "remember".
I forgot to buy some milk. I have forgotten...
I remembered to call my friend up. I have remembered...
It´s kind of confusing and again the problem is where to use the present perfect or not!?