1.3.8 - first zenshop - first question

I've an html banner which need to include a product name that has the é character in it.

in the banner manager I type
<p>A trial case of Glac&eacute;au Vitamin Water Energy Tropical Citrus for your employees. Give them that get-up-and go!</p>

If I save that and display the banner it's correct, but if I then reopen the banner in the banner manager the '&eacute;' has been replaced by the actual character. saving and displaying the banner again then shows a ? character instead of the correct e-acute.

I know it's down to the nature of the banner editor, but any ideas on how to make this more goof-proof?