Based on your experience, how do they charge (per employee, per transaction, etc) and how much does it cost, roughly?
Disclaimer: My data is from an answer to a LinkedIn question several years ago, so it's oudated at best.
There have also been other less significant issues, mostly regarding my status as a foreign employee. I speculate that it stems from a lack of properly engineered software on their end. In all cases, my problems would have been fixed by some logic along the lines of "If (employee.status == X && !taxesApplied.include(correctTaxes)) then trigger alert Y". Perhaps I'm too much of an engineer, but I find it hard to believe that a company that focusses solely on HR can even operate without this kind of automated check.
Not a good look for a company trying to sell a service that requires credibility.