JCrawf, you have been really very helpful. But I tell you what the concept of leaving open a possibility is still unclear and makes me feel that I am very dense.
Actually a few days ago, I visited a webpage and found that when I say “I have been to Paris several times”, this means that I have the experience of being to Paris several times. Now the question is “Why would I experience the same thing in the future?”, when I don’t intend to go to Paris in the future. I know your time is very precious, but I would like you to visit the page that I visited, because the future isn’t mentioned there at all.
Meanwhile, I am really very sorry, if I am bothering you, and thanks again for your help.
The present perfect can, at times, leave open the possibility of repeasting an action in the future. But that is not always the case.
If someone is playing poker, he might say "I have won 10 dollars." Because he is still playing , it is possible that he will win more. If the game is over, he can still use the present perfect because the event is very recent and still present in the speaker's mind. But the s[peaker could also use the past tense because the game is over. This is an unfortunate overlap between the present perfect and the simple past and this overlap becaomesd the choice of the speaker. No grammar rule can determine exactly how recent an event must be for a speaker to use the present perfect.
In the case of your note, the event is recent enough to use the present perfect. One would not use it with reference to a test that was administered a year ago, but days to even weeks would be OK in this situation. The mere fact that the father is trying to get the score changed is evidence that the action is still in the writer's "present".
The overlap between past simple and present perfect is very difficult for learners. I dare say it is difficult even for native speakers. For example, a BrE speaker would be far more likely to use present perfect in many of these overlap situations than AmE speakers. Americans tend to use the simple past in many of these situations. Both choices can be correct.