New Charges - Find By Key

Hi,

When I submit a charge via the XML API I get the following back once the submission is accepted.This value is embedded in a XML field called DocRequestKey
60c1c4eJxjZRd2YnXi4ol3yU8uzU3NK/FOrXTi4oh0djYOMI0Id+Lihcu4JJakgtTyxTvn5xYk5lX6leYmpRY5iXOYGkBgkzFEJjO12CO/tDjVyirC18c93MrKPbUEZoqVFYwVlFpYmlpcQo4edgYGBkYgZgJiZiBmAWJWIGYDYnYAE+w8/w==

I now need to find that charge via the above DocRequestKey value so I can update our records with the charge code. I think I can do that via the ChargeSearch resource on the XML API(link below), looks like DocRequestKey maps to the ContinuationKey field.
http://xmlgw.companieshouse.gov.uk/examples/ChargeSearch_response.xml

My question is:

Is there any way I can use the public API to find the new charge using that key above or anything else? It doesn’t seem to map to anything in the public JSON API as far as I can tell.

Any advice is appreciated.

Thanks