Wiring harness damage right after alternator/battery replacement

Hi all, looking for some outside perspective on a repair dispute.

Background: I have a 2020 Freightliner M2 (company truck). It went into a shop (Peach State Truck Centers, Norcross GA) for an alternator and battery replacement. Shortly after picking it up, we started having issues, and the shop diagnosed it as wiring harness damage on a follow-up visit. The estimate for this second repair is significantly higher than the original alternator/battery job.

The shop is not accepting any responsibility for the harness damage, and is treating it as a completely separate, unrelated issue.

My questions:

1. In your experience, how likely is it that harness damage showing up shortly after an alternator/battery job is actually caused by the shop's work (e.g., improper reinstallation, harness rubbing against something after being moved, incorrect wiring causing overheating)? Or is this a common coincidence with a truck this age/mileage?

2. What's the best way to push back on a shop that's denying liability? Any advice on documentation, questions to ask the service manager when I go in to discuss this with them?

Any input from mechanics or fleet/owner-operators who've dealt with something similar would be really appreciated. Thanks!