Student or Learner
The goods were splitted into two shipments. Would you please double check the second shipment, if there have 123 pcs, means no short-shipment. We think there maybe the transporter mistakenly counted the incorrect correct quantity. Furthermore, please confirm if you prefer to ship PO xxx by one 20' container as there is not other goods can be consolidated.
Not a teacher but a native speaker.
I would change it to something like this:
The goods were split into two shipments. Would you please double check the second shipment, there should be 123 pieces in total. We think the transporter may have made a mistake and sent the wrong quantity. Furthermore, could you please confirm if you prefer to ship to PO XXX by one 20' container, if so, no other goods can be accommodated.
Please note I am unsure on what you are trying to say in the last sentence, do you mean that if you ship the delivery in one 20' container, there wont be enough room? Also the word 'transporter' doesn't seem to fit, perhaps 'delivery company' or 'supplier' would be a better choice and flow better.