Monthly Payment Shock with Aidvantage

Looking for advice, thanks in advance!

I had been in administrative forbearance with all the SAVE tomfoolery until just recently when I was notified the admin forbearance period would end. Getting this news, I signed up for an IDR plan at the end of Juney and was quoted a ~$300 monthly payment for my adjusted gross income of ~$62,000 (repayment calculator on StudentAid.Gov confirmed that)…

I was gobsmacked when I was informed that I would be on the hook for just over $2,500 / month starting July 27th; I called Aidvantage and was told it would "correct" for my next bill, so I had to scrounge up some emergency cash to pay my July to avoid a missed payment. My August bill did not "correct," and the representative told me that I should re-certify my IDR (which I had just applied for at the end of June…). Has anyone been in a similar situation and had success getting the promised payments adjusted?