Hi everyone, new to the forum and on my second Lepin (1st:Green Grocer...awesome build, no missing parts; 2nd: Technic Porsche)

So I just received my Lepin Porsche from a seller on Aliexpress, shipped in bag, and sorted and started to build when I got to about step 50 and discovered I had 0 of the part the step required. Since I had everything sorted, it was easy to go through the Lego parts list and see that I have 6 different types of pieces missing for a total of 46 missing pieces, all technic beams and technic corner beams. I also have twice as many of the longest beams. I think I got a duplicate bag of the long beams, and am missing a bag of shorter beams, corner pieces. So my question to you fine experts: how do you deal with missing pieces?
I have sent a message to the seller to ask their policy, but waiting on this method could be very timely (and I am excited to build), I have also looked through Pick a Brick, and some of the missing pieces are not listed in the correct color (specifically the orange beams/corners). I'm considering just getting them through Pick a Brick, color differences be damned, but thought I'd ask how everyone else handles this issue?
This isn't nearly enough to prevent me from ordering more Lepin, have the Ghostbusters HQ on it's way as well.