The long term care facility I work at is generally terribly understaffed and I've been made to wait 30 minutes for a replacement to arrive but generally there's been someone on the unit to count the narcotics with me so I can leave sorta on time. It's not like I'm staying late because I haven't finished my work, my work is done almost always by the start of shift report. Today I'm especially pissed off for having been made to wait 45 minutes for a replacement to arrive. The supervisor kept telling me that "they're on their way" implying they were running late, but in reality they weren't scheduled to arrive until 4. The supervisor then told me that I wasn't allowed to leave because I'd be abandoning patients and that it's only company policy that I leave at 3:15 so they don't have to pay overtime and that I'm there until there's a replacement available. My coworker let me go first and was still stuck when I was walking off the unit. The only reason I haven't called off tomorrow yet is because I"m not sure that I won't just start screaming over the phone.

Is there literally anything I can do about this? I already have an exit strategy of cutting my hours and finishing my BSN, but they've also been dragging their feet for the past few months making the process take extra long but the end is mostly in sight so outright quitting isn't on the table yet.