The website is http://lotusmoonjewellery.com which is set up with zc1.5.5d and Ceon-URI-Mapping-4.5.2.

The .htaccess file in the root directory includes code to force URI to lowercase:

Code:
### beginning of section  THIS SECTION TO FORCE URI TO LOWERCASE
# AS PER simonholywell-force-lowercase-urls-rewrite-php AND stackoverflow questions 26032665
RewriteBase /
# force url to lowercase if upper case is found
RewriteCond %{REQUEST_URI} [A-Z] [OR]
RewriteCond %{QUERY_STRING} [A-Z]
# ensure it is not a file on the drive first
RewriteCond %{REQUEST_FILENAME} !-s
RewriteRule (.*) rewrite-strtolower.php?rewrite-strtolower-url=$1 [QSA,L]
### end of section
The problem occurs when we switch currencies, and we get a 404 error,
"http://lotusmoonjewellery.com/?currency=EUR&main_page=index"
with the comment,

"Error 404 - Not Found
The document you are looking for may have been removed or re-named. Please contact the web site owner for further assistance."

This is expected of course, with the currency "EUR" being in uppercase.
(in fact if we edit the uri to read "http://lotusmoonjewellery.com/?currency=eur&main_page=index" then the page is properly found, and with the correct currency).

We're hoping someone can suggest a quick fix to this problem?