Get online support
They are not 'patch cables' and not a do it yourself item, but are part of the NBN infrastructure. You need to ask TPG to get NBN to arrange to replace it. PM a mod here to arrange it.
EDIT: User options begin at the *output* of the NBN 'box' (NTD). There an ethernet cable from NTD to router is indeed a 'patch cable' and is the user's responsibility.