//Use the FundInstructions_Settle method
var client = new BFSServiceReference.bfsapiSoapClient();

var credentials = new BFSServiceReference.Credentials()
{
    UserName = bfsusername, //Username of administrative user in your instance of BFS
    Password = bfspassword, //Password of the administrative user in your instance of BFS
};

var target = client.FundInstruction_Settle(new BFSServiceReference.FundInstructions_SettleRequest()
{
    Credentials = credentials,

    identify = bfsidentifier, //Identifier is a unique token for your instance of BFS 

    ActionTriggerDataEntity = new FundInstructions_Settle()
    {
        BrickId = new Guid("02997b42-a061-463f-a81f-f7bbf2680846"),
        SettlementDate = TimeZoneInfo.ConvertTimeToUtc(DateTime.Parse("2016-05-01")),
        ValueDate = TimeZoneInfo.ConvertTimeToUtc(DateTime.Parse("2016-05-01")),
        SettledAmount = 30M
    }

});

Console.WriteLine(target.Message);