Question:
I gave my suit to the cleaners to clean. They by mistake tore the pants and sewed it back up. It was a non-Jewish cleaners. Do they have to pay me for a new pair of pants because it is worth less now or is sowing it up a good payment.
Answer:
The rule when someone damages an item of someone else is that they have to pay the amount that the item depreciated, not the original worth of the item. Meaning, that they don't have to buy the person a new item, rather they only have to pay for the actual damage. In your case, it would be the difference in the worth of the pants before it was ripped and after it was sewn up. Unfortunately this isn't much money, because the pants were already a used pair of pants, and now it is a used pair of pants with a sewn rip. However you can ask for this amount of money, and if they offer you more, you may take it.
Sources:
CH:M 403-1, 387-1, Pischei Choshen Nezikin 10-22.