HSA contacted us saying we overpaid HSA in 2020. Not enough funds in account to withdraw to correct. Already filed taxes. How should I fix this?

My wife and I were a part of a family HSA through my employer last year which included employee contributions. On Jan 1st, we switched to her employer's insurance. Since then, the HSA provider has closed our original account and moved the funds over to a new account. We have been trying to use all the funds in that account in order to consolidate.

I was notified by the HSA last week that apparently we overcontributed last year by ~$900. Currently there is $25 in the account. There's not enough to withdraw in order to correct the balance. I have already filed my 2020 taxes through TurboTax, but I didn't notice a warning about excess contributions at the time. Since I can't withdraw the funds, how should I correct this problem?