https://www.gruss-software.co.uk/Excel/Chase_Price.xlsThis spreadsheet demonstrates using the UPDATE trigger to keep a lay bet at the front of the queue by beating the best back odds.
Put "1" in the enabled column to activate chasing and the maximum odds you will lay up to in the max odds column.
There is a potential pitfall with this method. For example if your stake is £2. The problem is when there is money below £2 in the queue. If say £1 is at the front of the queue BA won't display it. UPDATE puts you at the front of the queue so it's now £3 at the front. UPDATE will again put you at the front. Because only £1 is at the next best odds it won't be displayed so UPDATE will trigger again to reduce your offer. Your offer will join the £1 again so it will trigger another UPDATE to put you at the front. It can get stuck in this cycle. This could cause a large number of transactions so you may want to modify this example for your needs. It should however give you an idea of how UPDATE can be used.
Please be aware that this is only an example. We cannot accept responsibilty for any transactions charges you encounter as a result of using this spreadsheet.
Note: This example assumes you do not tick "UPDATE trigger appends 'N' to new bet ref" when linking to Excel.