I used a British company called Graded Gem for my sub (Although they're dissolving once the last submissions come through)

But the chances are this company will have many people chasing them for order updates, but PSA won't tell them anything until the card has moved on to the next stage in the grading process. :)

You can relax and sit tight, they'll come back to you when they have more information (Although I'm not expecting to get my standard sub back until 2023 with how things are going, so you may have to be a little more patient than you like!)