CRM Dynamics 2013 Plugin failed to import CSV file

I have a CRM Plugin that fires on an update of a field on the form, the plugin then should utilize the Import capabilities of the SDK to Import CSV Records into Dynamics, I get the following error

Request for the permission of type 'System.Security.Permissions.FileIOPermission, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089' failed.

I have registered the Plugin in Isolation Mode set to NONE, not Sandbox but I still get the error, any Ideas as to why this is happening and how I can resolve it. It fails on the ImportFile part which is encapsulated in the ImportData function. This is an on-premise version of CRM.

Please see my Plugin Code below

public void Execute(IServiceProvider serviceProvider)
    {
        ITracingService tracingService = (ITracingService)serviceProvider.GetService(typeof(ITracingService));
        IPluginExecutionContext context = (IPluginExecutionContext)serviceProvider.GetService(typeof(IPluginExecutionContext));

        if (context == null)
        {
            throw new ArgumentNullException("loaclContext");
        }

        if (context.InputParameters.Contains("Target") && context.InputParameters["Target"] is Entity)
        {
            Entity supplyClaimsEntity = (Entity)context.InputParameters["Target"];

            if (supplyClaimsEntity.LogicalName != "new_supplierclaimsupdate")
            {
                return;
            }

            IOrganizationServiceFactory serviceFactory = (IOrganizationServiceFactory)serviceProvider.GetService(typeof(IOrganizationServiceFactory));

            IOrganizationService service = serviceFactory.CreateOrganizationService(context.InitiatingUserId);

            string entityBeginUpload = "Start Upload";
            try
            {

                string filePath = (@"C:\Team CRM\Warp.csv");

                ImportData(service, new_topproducts.EntityLogicalName, filePath);

            }

            catch (FaultException<Microsoft.Xrm.Sdk.OrganizationServiceFault> ex)
            {
                Console.WriteLine("The application terminated with an error.");
                Console.WriteLine("Timestamp: {0}", ex.Detail.Timestamp);
                Console.WriteLine("Code: {0}", ex.Detail.ErrorCode);
                Console.WriteLine("Message: {0}", ex.Detail.Message);
                Console.WriteLine("Inner Fault: {0}",
                    null == ex.Detail.InnerFault ? "No Inner Fault" : "Has Inner Fault");
            }
            catch (System.TimeoutException ex)
            {
                Console.WriteLine("The application terminated with an error.");
                Console.WriteLine("Message: {0}", ex.Message);
                Console.WriteLine("Stack Trace: {0}", ex.StackTrace);
                Console.WriteLine("Inner Fault: {0}",
                    null == ex.InnerException.Message ? "No Inner Fault" : ex.InnerException.Message);
            }
            catch (System.Exception ex)
            {
                Console.WriteLine("The application terminated with an error.");
                Console.WriteLine(ex.Message);

                // Display the details of the inner exception.
                if (ex.InnerException != null)
                {
                    Console.WriteLine(ex.InnerException.Message);

                    FaultException<Microsoft.Xrm.Sdk.OrganizationServiceFault> fe = ex.InnerException
                        as FaultException<Microsoft.Xrm.Sdk.OrganizationServiceFault>;
                    if (fe != null)
                    {
                        Console.WriteLine("Timestamp: {0}", fe.Detail.Timestamp);
                        Console.WriteLine("Code: {0}", fe.Detail.ErrorCode);
                        Console.WriteLine("Message: {0}", fe.Detail.Message);
                        Console.WriteLine("Trace: {0}", fe.Detail.TraceText);
                        Console.WriteLine("Inner Fault: {0}",
                            null == fe.Detail.InnerFault ? "No Inner Fault" : "Has Inner Fault");
                    }
                }
            }