diff --git a/lib/services/Invoice.js b/lib/services/Invoice.js
index 55dd16e..add5b61 100644
--- a/lib/services/Invoice.js
+++ b/lib/services/Invoice.js
@@ -15,8 +15,33 @@ function InvoiceService(config) {
     this.config = config;
 }
 
+/* http://developers.freshbooks.com/docs/invoices/#invoice.sendByEmail */
+InvoiceService.prototype.sendByEmail = function(id, cb) { //cb(err, client)
+    var data = {
+            invoice_id: id
+        },
+        options = {
+            method: 'invoice.sendByEmail',
+            url: this.config.url,
+            token: this.config.token
+        };
+
+    utils.callAPI(data, options, function(err, result) {
+
+        if (err) {
+            cb(err, null);
+        }
+        else if (!result) {
+            cb(null, null);
+        }
+        else {
+            cb(null, result.client || null);
+        }
+    });
+};
+
 /* http://developers.freshbooks.com/docs/invoices/#invoice.list */
-InvoiceService.prototype.list = function(cb) { //cb(err, invoice, metaData)
+InvoiceService.prototype.list = function(data, cb) { //cb(err, invoice, metaData)
 
     var options = {
         method: 'invoice.list',
@@ -24,13 +49,15 @@ InvoiceService.prototype.list = function(cb) { //cb(err, invoice, metaData)
         token: this.config.token
     };
 
-    var filters;
-    if (typeof arguments[1] === 'function') {
-        cb = arguments[1];
-        filters = arguments[0];
+    var filters = data;
+    var callback = cb;
+
+    if (typeof data === 'function') {
+        callback = data;
+        filters = {};
     }
 
-    utils.callAPI(null, options, function(err, result) {
+    utils.callAPI(filters, options, function(err, result) {
 
         if (err) {
             cb(err, null);
diff --git a/lib/services/Payment.js b/lib/services/Payment.js
index c2013c2..7475b36 100644
--- a/lib/services/Payment.js
+++ b/lib/services/Payment.js
@@ -16,7 +16,7 @@ function PaymentService(config) {
 }
 
 /* http://developers.freshbooks.com/docs/payments/#payment.list */
-PaymentService.prototype.list = function(cb) { //cb(err, payment, metaData)
+PaymentService.prototype.list = function(filters, cb) { //cb(err, payment, metaData)
 
     var options = {
         method: 'payment.list',
@@ -24,13 +24,12 @@ PaymentService.prototype.list = function(cb) { //cb(err, payment, metaData)
         token: this.config.token
     };
 
-    var filters;
-    if (typeof arguments[1] === 'function') {
-        cb = arguments[1];
-        filters = arguments[0];
+    if (typeof arguments[0] === 'function') {
+        cb = arguments[0];
+        filters = {};
     }
 
-    utils.callAPI(null, options, function(err, result) {
+    utils.callAPI(filters, options, function(err, result) {
 
         if (err) {
             cb(err, null);
diff --git a/lib/services/utils.js b/lib/services/utils.js
index 99a4ffa..7f0fdcb 100644
--- a/lib/services/utils.js
+++ b/lib/services/utils.js
@@ -1,6 +1,7 @@
 
 var xml2js = require('xml2js'),
     request = require('request'),
+    builder = require('xmlbuilder'),
     fs = require('fs');
 
 function callAPI(data, options, cb) {
@@ -13,24 +14,18 @@ function callAPI(data, options, cb) {
         options = {};
     }
 
-    data.$ = {
-        method: options.method
-    };
-
-    var buildOpts = {
-        rootName: 'request',
-        xmldec: {
-            version: '1.0',
-            encoding: 'UTF-8'
-        }
-    };
-
-    var builder = new xml2js.Builder(buildOpts);
+    data['@method'] = options.method;
 
     var xmlStr;
     try {
-        xmlStr = builder.buildObject(data);
+        xmlStr = builder.create({
+            request: data
+        }, {
+            version: '1.0',
+            encoding: 'UTF-8'
+        }).toString();
     }
+
     catch(e) {
         cb(e, null);
         return;
diff --git a/package.json b/package.json
index a30b703..3f3dcf5 100644
--- a/package.json
+++ b/package.json
@@ -25,6 +25,7 @@
   "homepage": "https://github.com/hashdog/node-freshbooks-api#readme",
   "dependencies": {
     "request": "^2.60.0",
+    "xmlbuilder": "4.2.1",
     "xml2js": "^0.4.10"
   },
   "devDependencies": {