PSA for my contractor friends: Avoid working with US Tech Solutions if you can. TLDR: Their payroll staff and systems are the textbook definition of incompetent and shady.
All throughout 2019 not only could their system not make use of the simple timesheet files the client firm was sending (a three column excel sheet), but they frequently shorted my paycheck. Fighting them to pay the full amount was also a PitA, as they'd demand a paper trail the length of a CVS receipt. The few times when things did go smoothly in the process and they correctly paid out for an 80 hour two-week period, they also threatened to take funds out of the next check, accusing me of "overbilling" unless I gave them the same documentation mentioned in the previous sentence.
But the latest and most egregious F-U they've pulled on me is that they severely underpaid my taxes from each check, and now I'm stuck with a $4000 tax bill that we REALLY don't need right now trying to save for a house... Luckily I do my taxes early so as to be able to plan for surprises like this, but that doesn't make it any more excusable.
As you can imagine, I'm very happy to be employed directly by the client now and won't have to deal with that BS anymore.