With E*trade what I do when an order doesn't look like filling at my price, I can adjust my ordered number of shares and price, being careful to stay on or under the original amount of money and the order goes through with two or some times three different buy prices and only the one original lot of brokerage.
Calculate the cost of the shares you have plus the full brokerage, subtract that from your original order amount, then divide the balance by the price you want to pay, rounding down to meet or under your original amount.
Might work on other platforms too.