ISP packet loss question/advice

Just built out a new internal network for a medium sized business in a rural part of the North East. Everything is working great, except general internet. Local ISP is small, but has a solid fiber network. However, we are getting nasty packet loss from the hop immediately after our ISP's boundary. And it isn't just our location. It is the entire town.

Pathping is clean out of the gate, but as soon as it hits the hop right after our small ISP (in this case, a series of Cogentco hops) we experience 2 to 10% packet loss.

We reached out to the small ISP with our data and got the ole "it's not our network" reply and "it's normal summer congestion." My questions for you fine folks...

1. Am I wrong in thinking that they should have some relationship with the connection that they are passing their traffic off to? Wouldn't that be their upstream provider? And shouldn't they be able to reach out to them about this or escalate the issue? Or is that not how it works in situations like this?

2. Any advice on how to approach this problem? It's totally up to our ISP to resolve, right? How would be the best way to get them to agree with that?