This is because auto regressive LLMs work on high level "Tokens". There are LLM experiments which can access byte information, to correctly answer such questions.
Also, they don't want to support you omegalul do you really think call centers are hired to give a fuck about you? this is intentional
For usage like that you'd wire an LLM into a tool use workflow with whatever accounting software you have. The LLM would make queries to the rigid, non-hallucinating accounting system.
I still don't think it would be anywhere close to a good idea because you'd need a lot of safeguards and also fuck your accounting and you'll have some unpleasant meetings with the local equivalent of the IRS.