It's missing a comma and/or em dash.
"I could not get past your first level support, who -- and I do mean this harshly -- sounded like they didn't pass first year business school."
"I could not get past your first level support, who -- and I do mean this harshly -- sounded like they didn't pass first year business school."
They mentioned being a "case that falls outside [Stripe's] remit", and that Stripe didn't "give them the benefit of the doubt".