Charged way more at dentist than what they billed insurance - what's my recourse?

So I'm dealing with this frustrating situation and could use some advice on how to handle it.

Back in early fall, I went for my routine checkup and cleaning plus getting a temporary crown after having root canal work done previously. Right before they started the x-rays, the front desk told me they accept my insurance company but not my particular plan, so I'd need to pay everything upfront and file for reimbursement myself.

I really needed to get this done since I'd been postponing it, so I reluctantly charged $2,154 to my card. Been basically living paycheck to paycheck trying to knock this balance down ever since.

Filed my claim like they instructed me to, but it got rejected. Called my insurance and they explained the dental office has to submit it, not patients. Turns out the office had already done this - but here's where it gets weird. They only submitted $1,280 to insurance, not the full amount I paid them. My portion after insurance processed is $293.

So now I'm confused about what I actually owe. I paid them over two grand, but they're telling insurance the total cost was only $1,280? The billing department said they'd call me back to explain but that was days ago and nothing.

Planning to call again Monday but wondering what my options are here. Should I be getting most of my money back since there's such a huge difference between what I paid and what they claimed? Or am I still on the hook for both amounts somehow? This whole thing has really messed up my budget and I'm pretty stressed about it.

Anyone dealt with something similar?