Two unique Greek words appear here, one translated as "debt" and the other translated as "because." The word "debt" appears many times in translating Jesus's words and in this parable, but a variety of words are used by him, four different nouns, and two different verbs. All are from the same root except one of the nouns. The word translated as "because" is not one of the many common words meaning "because," but one that refers to specific occurrence in the past.
The "said" here is in the present tense, "says," which is different from all the other verbs, which are in the "story" tense that has the sense of "at that time." It sticks out here, making it seem intentional and funny, emphasizing the word.
Jesus uses the same rare (for him) word twice in this verse, one he used earlier in the story. Here, he uses it in two different senses. This word is used a half dozen times by Jesus and it is translated into almost as many different English words. Here, it is translated as "called" and "desirest" in the KJV and "called" and "begged" in the NIV. All of those translations are confusing this with other Greek words. The sense is "called out to." When used by a king, the "called out to" sense is "summoned." When used by a supplicant, the sense is "cried out to." This is the punchline of the verse so the repetition and the change in meaning serves a purpose.
Christ's Words in Matthew as a Guide to 40 Days of Prayer.