Oh for the love of tech, do chase them. This absolutely has to be in void of the terms of your trial take them to court. If not, then at the very least name and shame the company, so some dumb manager orchestrating this silly theft will get fired and someone more mature can be rotated in.
I've seen huge delays spanning months, and needing approvals from the very top, which you need to keep following up and makes the entire process a very painful experience.
Maybe it's by design to reduce costs but it happens even in places where the budget is overflowing and underused.
Payments won't happen until things are literally burning or production is about to go down tomorrow and the fear of the client getting super mad(that a relatively small payment couldn't be made in months) will drive some urgency. Sometimes not even then, so people are left with bad choices, let something terrible happen or make terrible workarounds like in the article. This results in a drive to only use free tools or make do with none.
I hope this results in better and easier accounting practices, which is probably ripe for disruption.