Acknowledge their concern first then tell them either “I’ll do it youre way”, “Let’s compromise” or pound sand in the nicest way you can. I get more success with above but I deal with clients. Most of it is them wanting to be heard.
Yup they will just send you a new one. I’ve been using the same black jansport bag for > 5 years. As far as I can see the new ones they sent has the same quality as more than 5 years ago.