What mitzvah is there in either case?
It is perfectly reasonable, and even expected, to pursue restitution through appropriate mechanisms. (For civil cases today, Jews are expected to go through a rabbinic panel before the secular court system, for example.)
As was stated previously, the blanket forgiveness that's recommended to give people before Yom Kippur explicitly excludes "money I could still successfully claim through a beit din [rabbinic panel]."
Update: okay there is going to be a range of "normal" here; if we are talking one dollar and it was a mistake unlikely to happen again, vs. someone totals your car. As pointed out in the comments, in Megillah 28a it considers someone very meritorious to be lenient about their money; however the example it then gives is Job, expecting you to flip to Bava Basra 15b, which is basically that he would tell shopkeepers "keep the change" when making change would have been troublesome. Rashi adds in it seemed wrong to him to be a stickler about a minor matter.