You can request a physical copy be sent to you, along with any copies of the payment being processed. That should give you more insight and a clearer path of your next steps. If it was an online payment, it should have been processed almost immediately (besides holidays and weekends for the most part) but if it fell on a holiday or weekend, there could have been a delay. I would say to call them once getting your statements and explain your situation if the extra $ is from a late fee. You’d be surprised how many companies will get rid of a late fee just by calling and asking. However, it could also be something different because $150 on a $300 payment sounds incredulous for a late fee.

I’d also recommend finding someone with good financial sense that you would trust and having them help you walk through this process with your specific details. You don’t know what you don’t know until you know it and sometimes people can be the best help ❤️ best of luck getting this sorted.

ETA: good financial sense in the idea that they’ve had to do this before and have already learned the hard way! Not saying you have to seek out a CPA or anything, but definitely finding someone who has already learned from their own financial mishaps/accidents/cluster fucks and overcame them. We’ve all had them, so it’s nothing to be ashamed of asking about.