Curly braces in GUIDs causing issues

Hi everyone, hoping you can give me some ideas on a problem I face.

I'm using a proxy to access Sharepoint 2013, and have resolved a number of issues already with this. My most recent problem is that all of the Sharepoint functions now seem ok, apart from where curly braces {} are used in URLs. The proxy is very unhappy with these, and refuses to pass URLs with them present. This breaks things like uploading of documents.

I wonder if there is a way of ensuring (at the sharepoint side) that it doesn't use curly braces but instead uses URL encoded versions? Or perhaps some other solution?

Thanks,

Matt