== Your web page ==
Refer to the developers web site for a full set of options, instructions and problem solving.
Obtain the file iframeResizer.min.js and copy it to your web server.
Make sure to use the same version number as the iframeResizer.contentWindow.min.js which has been included on the booking page. (in this example 3.5.3)
The file can be downloaded from the developer site or from https://beds24.com/include/iframeresizer/3.5.3/iframeResizer.min.js
Remove any height parameter from your iframe and add the script after the iframe, if necessary change the src path to the location of your iframeResizer.min.js file.
If you prefer, you can set a fixed iframe width in pixels rather than a percentage.