Set a parameter value with comma character inside

I need to update an xprofile field value calling:
https://[www.mysite.com]/api/user/update_user_meta/?cookie=%5Bmycookie%5D&insecure=cool&meta_key=geocode_3&meta_value=40.9954763,14.4213379

The “geocode_3” field is related to “BP xProfile Location” plugin (https://www.philopress.com/products/bp-xprofile-location/)
Sending a coordinate value with comma separated “latitude,longitude” your plugin
update the field, response “update=true”, but when i request these field value calling
https://[www.mysite.com]/api/user/get_user_meta/?cookie=%5Bmycookie%5D&user_id=%5Buserid%5D&insecure=cool response a wrong format value:
“geocode_3″:”a:2:{i:0;s:10:\”40.9954763\”;i:1;s:10:\”14.4213379\”;}”}

How to avoid interpret the comma as parameter delimiter? I need to pass a simple string with comma inside… I’ve already try to encode the url parameter; comma became a “%2C”, but the result does’nt change.

Simone