Would A Lawyer Be Worth It?

This is for a problem my mother is having with the IRS. We live in Maryland.

She's always filed 'self employed' and always pays her share, no exemptions and is never late on payments.

But for the 2023 tax year she sent in her check as usual, with her info in the memo as her accountant suggested and the IRS cashed the check, but never posted it to her account. So she lost the money from the check but they sent her a letter saying she hasnt payed anything yet and started accruing interest on her taxes. She had multiple phone conversations with various people, the first guy who told her he opened a 'ticket' or something for her and she should keep paying as she normally does and when they resolve it they will remove the interest from her account because it was their error. My mom sent in another check (same amount as first) to continue payments as normal but they did the same thing again! Cashed it and didnt post it to her account. The second lady she spoke on the phone with straight up did not believe her, and afterwards she had an in person meeting at their office in baltimore where the employee checked the cameras, found the first check being cashed, but then didnt really do anything about it after?

A few months ago she got a call from a 'lawyer' from the IRS (a legit number not a scam) who told my mother her job is to invesitage and resolve issues people are having with the IRS (I really doubt that, shes probably cleaning up their mess to avoid legal troubles). This lady asked my mom to forward her all the documents and anything to this issue and of course my mother being the type to believe the US government is perfect and could never do no wrong, she sent her everything and is fully cooperating.

But since then she hasn't heard from this lady at all and has gotten no updates, after the second check was cashed and not posted she has stopped paying altogether, I don't know what her plan is for the 2024 tax year. Since the first check was cashed and not posted I have been telling her she should absolutely get a lawyer and that everyone makes mistakes even the IRS but she should protect herself incase they try to turn it around on her. She doesnt make much and I am scared for her, im ???? this close to getting her a lawyer and just paying for it myself, I also don't make much more than her but I would feel guilty if she ended up getting screwed over because of their mistakes.

TL;DR IRS Cashed checks my mother sent in for her self employement taxes for the 2023 year and are not posting to her account, acting as if she hasn't payed anything. Amidst her efforts to reach out and resolve this they haven't done a thing and Im scared its going to fall back on her when filing for 2024.

Would a lawyer help resolve this? Could she be compensated extra for this (i.e. get money for a new car or something?) She's already sent them over 5k thats unaccounted for.

Thank you for your time and advice.