[SOLVED] System.ServiceModel.FaultException'1' revised

I have a service reference defined in my project (created in vs2013) and the bindings in the AppConfig are defined thus;

<system.serviceModel>
        <bindings>
            <basicHttpBinding>
                <binding name="BasicHttpBinding_IERSAPIService" maxReceivedMessageSize="2147483647"/>
            </basicHttpBinding>
        </bindings>
        <client>
            <endpoint address="http://staging.saffire-online.co.uk/ERSAPIService/ERSAPIService.svc"
                binding="basicHttpBinding" bindingConfiguration="BasicHttpBinding_IERSAPIService"
                contract="ErsTestSite.IERSAPIService" name="BasicHttpBinding_IERSAPIService" />
        </client>
    </system.serviceModel>

Within this service reference there is a function:

Public Function salesXMLCheck(ByVal xmlString As String) As String Implements ErsTestSite.IERSAPIService.salesXMLCheck
            Return MyBase.Channel.salesXMLCheck(xmlString)
        End Function

If I pass the following string ('Hello') into that function it returns the following:

<?xml version="1.0" encoding="UTF-8"?>
<ers itemtype="Sales Note" doctype="RET" status="NAK" errorcode="E200 [XML Parse Error]" date="2015-06-10 08:02:42" />

Essentially the service has received my message, parsed it , realised it's not properly formatted xml and sent back a message to that effect. To my mind at least that suggests that I am at least connecting with the service successfully.

However if I then call this function again, but this time passing in some valid xml;

<?xml version="1.0" encoding="UTF-8"?>
<ers uname="apiuser" pword="apipassword" myAttribute="fooBar" anotherOfMyAttributes="123456">
    <salesnote snType="S" action="INSERT" salesContractRef="" saleDate="20090807" auctionID="14" logBookNums="" landingDecNums="" vesselName="SEA ANGEL" vesselPln="TN103" vesselMasterOwner="ARRANBRAE LTD" landingDate1="20090807" landingDate2="" landingDate3="" countryOfLanding="GBR" landingPortCode="GBADR">
        <salesline speciesCode="NEP" faoAreaCode="27" ZoneCode="VB1" disposalCode="HCN" freshnessCode="A" sizeCode="2" presentationCode="HEA" stateCode="FRE" numberOfFish="" weightKgs="52" value="765" currencyCode="GBP" withdrawnDestinationCode="OTH" buyerReg="201" salesContractRef="B4123"/>
        <salesline speciesCode="WHB" faoAreaCode="27" ZoneCode="VB2" disposalCode="HCN" freshnessCode="A" sizeCode="3" presentationCode="GHT" stateCode="FRE" numberOfFish="" weightKgs="12" value="55" currencyCode="EUR" withdrawnDestinationCode="BOL" buyerReg="201" salesContractRef="TT45687"/>
        <salesline speciesCode="JAD" faoAreaCode="27" ZoneCode="VIID" disposalCode="COV" freshnessCode="C" sizeCode="2" presentationCode="FIL" stateCode="FRE" numberOfFish="" weightKgs="300" value="330" currencyCode="GBP" withdrawnDestinationCode="GIF" buyerReg="201" salesContractRef="B5687"/>
    </salesnote>
</ers>

I end up with a System.ServiceModel.FaultExceptio'1' giving me the additional message; @String must be exactly 1 character long'.

the error is thrown on the returnsEditor.text line in the function below;

Dim value As String = File.ReadAllText("C:\Users\Public\Documents\View to Learn\SNADD.xml")

        Using ters As New ErsTestSite.ERSAPIServiceClient
            ters.Open()
            returnsEditor.Text = ters.salesXMLCheck(value)
            ters.Close()
        End Using

Clearly the service connection works or the same message would be thrown when I substitute 'Hello' as the parameter to the function, so why is this error being thrown when I try and submit valid xml?

EDIT

when I look closely at the stack trace I see the following:

   at System.Convert.ToChar(String value, IFormatProvider provider)
   at System.Convert.ChangeType(Object value, Type conversionType, IFormatProvider provider)
   at System.Data.Linq.DBConvert.ChangeType(Object value, Type type)
   at Read_FreshnessGrade(ObjectMaterializer`1 )
   at System.Data.Linq.SqlClient.ObjectReaderCompiler.ObjectReader`2.MoveNext()
   at System.Collections.Generic.List`1..ctor(IEnumerable`1 collection)
   at System.Linq.Enumerable.ToList[TSource](IEnumerable`1 source)
   at ERSAPIService.Helper.SalesNoteHelper.SalesNoteCheck(XDocument xlowerDocument, XDocument xmlOutput, String rootName, String userId) in C:\Users\ravneet.sodhi\Desktop\ERSAPIService\ERSAPIService\Helper\SalesNoteHelper.cs:line 262
   at ERSAPIService.Helper.SalesNoteHelper.salesXMLCheck(String xmlString) in C:\Users\ravneet.sodhi\Desktop\ERSAPIService\ERSAPIService\Helper\SalesNoteHelper.cs:line 71
   at ERSAPIService.ERSAPIService.salesXMLCheck(String xmlString) in C:\Users\ravneet.sodhi\Desktop\ERSAPIService\ERSAPIService\ERSAPIService.svc.cs:line 1776

As I am most definitely not raveet.sodhi does this mean that the xml is actually being successfully passed to the other end but that there is an issue in the service there?