I had to leave my car with my parents because of a flat tire and a slipping clutch( I didn't want to drive 200+ miles on either).

Ordered the tires 205/60 R13 off the internet and had them shipped to my parents house. Father takes the car to an installer for me and they claim that I stripped the threads, putting on the spare (more likely their impact wrench).

If i'm understanding this correctly, the treads that have been stripped are on the rear axle shaft. What are my options/procedure for fixing this? Any links or experienced advice would be really appreciated.

Note: I'm using after market rims and lugs that skrew into the rear axle shaft on the other side of the drum.