Requested 2018 partial refund with balance applied to following year (2019) => received entire refund amount via direct deposit

IRS appears to have ignored my instructions to roll a large portion of a refund due to the following tax year - normally not a big deal, but this relates to late filing of my 2018 return, and the subsequently filed 2019 and 2020 returns which have not yet been processed and reflected the application of the 2018 refund to 2019 estimated tax payments.

• 2018 Fed return filed in 2021 => sizeable refund due, so no penalty/interest due to late filing
• 2018 return was filed (and IRS processing completed) within 3 yr period for refund claims (10/15/22, adj for 2018 extension)
• 2018 return indicated I wanted a small portion of the overpayment to be refunded (to indicate processing had been completed) and the balance applied to 2019 taxes (i.e  Total Refund $5100, $100 to be refunded and $5000 to be applied to 2019).
• Several days ago, the entire refund amount ($5100) was deposited to my bank account.
• Reviewed 2018 transcripts online (below) - IRS apparently made no adjustments made to total refund amt
  • Refund Amount                                                                            -  100
  • Applied to Next Year’s Estimated Tax                                      5000
  • Estimated Tax Penalty                                                                        0
  • Tax on Income Less State Refund per Computer                         0
  • Bal Due/Over Pymt Using TP Fig per Computer                   -5100
  • Bal Due/Over Pymt Using Computer Figures                        -5100
  • Form 8888 Total Refund Per Computer                                         0
• Unable thus far to reach an IRS agent at [phone number removed] (“…high call volume”, disconnects)
• 2019 and 2020 returns have already been filed, and those returns reflect the refund rollover amts

Questions:

1. Does this appear to be an IRS error?  Any reason come to mind that the IRS would ignore/overrule my refund instructions (confirmed in the transcript) - has never happened before when I have filed late
2. What should I do => am concerned 2019/2020 returns will be processed and IRS records would not reflect the 2018 amt applied to the 2019 tax liability (sizeable 2019 refund was largely applied to the 2020 tax liability).  Letter correspondence will probably be very slow to resolve, and unsure whether I'll be able to reach an agent by phone.  If I am unable to get this resolved, I may become subject to some penalties for late filing and/or interest on underpayment of estimated taxes for subsequent years.