Need to remove unusual character in source

I've come across a character in the source that I need to remove.

I'm using Saxon 8, XSLT 2

the character is and its a control character

0x18 CAN

I've tried using character-map while defining the character as an entity as such
<!ENTITY controlChar18 "&#x18;">

<xsl:character-map name="testMap">
   <xsl:output-character char="&controlChar18;" string="REMOVEDCHAR" />
</xsl:character-map>

<xsl:result-document use-character-maps="testMap".../>

the error message I recieve is
SXXP0003: Error reported by XML parser: Illegal XML character:  &#x18;.

I've tried using ANT to clean it out but with no luck using native2ascii or
escapeunicode

Can this be done or do I need to ask the client to remove it from their data,
which might not be an option?

Any help or insight would be greatly appreciated.

Marijan Madunic