I am unaware of any such service. These KT lock assemblies are notoriously flimsy, and the crappy chrome-ish plating eventually flakes off. There are electroplate companies that could replate it if you disassembled it for them.
A new one costs a ridiculous ~$600.
Many of us have replaced the KT with a conventional RV latch (with an integrated deadbolt) such as this:
Problem is that this new latch does not fit in the same hole as the KT, so the old hole has to be patched. I believe Inland RV and outofdoorsmart.com both sell kits that include the patches, Olympic rivets, etc.