Your broker is absolutely correct.
you sold 100 shares at a loss on 9/28
the 10/16 purchase triggered the wash sale. it's not the order that counts. the wash sale rule applies to any purchase of the same security within 31 days of a loss sale of the same security. so the 9/28 loss is disallowed and that loss is added to 100 shares purchased on 10/16. maybe online access will allow you to see the cost basis for each purchase, if not the monthly statement for October should give details. what you should see for the 10/16 purchase is what the trade confirm shows as the cost + the amount of the 9/28 wash sale loss. - maybe the broker will break it down into 2 purchases of 100 shares with 100 having 1/2 the original cost and the other 100 having the original cost + the loss
