Remember to use quotes when writing dialogue. Also, I assume that
hold(above) is a typo for the intended told.
These minor things aside, consider these possibilities:
1) The writer can suggest stress on words by italicizing key phrases to show an intended emphasis:
But you have told me that you were going to."2) The addition of "already" to the verb phrase "have told" increases the idea of something that has been discussed more than once and agreed upon:
"But you have already told me (that) you were going to."3) Finally, don't forget that the writer may add an exclamation point followed by a description of the speaker's inflection in order to leave no question in the reader's mind about the speaker's anger:
"But you have already told me you were going to!" he said angrily.
Student or Learner