Past simple or present perfect for the number of times of doing something.
I have just called my friend on her cell**,** but I couldn't reach
her. Now I want to write her to inform her about it. Would you please
tell me which one is correct?
" I have called you three times**,** but I couldn't reach you.
Or
" I called you three times**,** but I couldn't reach you."
COMMENTS:
The past perfect is better, but the simple past is fine. You can also say "I've called . . . ."
Since you didn't actually reach her, it would be more exact to say, "I've tried calling . . . ." or "I tried calling . . ."
NOTE:
Use commas to connect the clauses of compound sentences.