When can purchase 16gb ECC SODIMM for my 3510

Well after several attempts through all the normal channels, I am coming here in hope that my issue can be resolved. I am looking to purchase an additional 16 GB DUAL IN-LINE MEMORY MODULE, 16GB, 2133, 2RX8, 8G, DDR4, EXPANDABLE SYSTEM dell number 370-ACOZ (taken from my configuration info) for my new precision mobile workstation 3510 with XEON processor.

The part number on the memory in my system reads

SK Hynix (Korea) 16GB 2RX8 PC4-2133P-TH0-11