diff --git a/BookAStar/BookAStar/BookAStar.csproj b/BookAStar/BookAStar/BookAStar.csproj
index bc7344be..ec918cbb 100644
--- a/BookAStar/BookAStar/BookAStar.csproj
+++ b/BookAStar/BookAStar/BookAStar.csproj
@@ -47,6 +47,7 @@
     <Compile Include="Behaviors\StarBehavior.cs" />
     <Compile Include="Constants.cs" />
     <Compile Include="Converters\BooleanToObjectConverter.cs" />
+    <Compile Include="Converters\EnumConverter.cs" />
     <Compile Include="Converters\GenderConverter.cs" />
     <Compile Include="Converters\RatingText.cs" />
     <Compile Include="Extensions\ImageResourceExtension.cs" />
@@ -143,7 +144,7 @@
     <Compile Include="ViewModels\BillingLineViewModel.cs" />
     <Compile Include="ViewModels\ChatViewModel.cs" />
     <Compile Include="ViewModels\DashboardViewModel.cs" />
-    <Compile Include="ViewModels\EstimateViewModel.cs" />
+    <Compile Include="ViewModels\EditEstimateViewModel.cs" />
     <Compile Include="ViewModels\UserLoginViewModel.cs" />
     <Compile Include="ViewModels\ViewModelBase.cs" />
     <Compile Include="Views\MarkdownView.cs" />
diff --git a/BookAStar/BookAStar/Pages/EditBillingLinePage.xaml b/BookAStar/BookAStar/Pages/EditBillingLinePage.xaml
index dd8b4f38..9f8ad878 100644
--- a/BookAStar/BookAStar/Pages/EditBillingLinePage.xaml
+++ b/BookAStar/BookAStar/Pages/EditBillingLinePage.xaml
@@ -63,12 +63,12 @@
         <Entry.Behaviors>
           <behaviors:DecimalValidatorBehavior x:Name="unitCostValidator" />
         </Entry.Behaviors>
-      </Entry>
-      <Label Text="€" Style="{StaticResource BigLabel}" />
-      <Image  x:Name="unitaryCostSuccessErrorImage"
-                Style="{Binding Source={x:Reference unitCostValidator}, 
+        <Image  x:Name="unitaryCostSuccessErrorImage"
+                  Style="{Binding Source={x:Reference unitCostValidator}, 
                                 Path=IsValid, 
                                 Converter={StaticResource boolToStyleImage}}" />
+      </Entry>
+      <Label Text="€" Style="{StaticResource BigLabel}" HorizontalTextAlignment="Start"/>
     </StackLayout>
     <Button Text="Valider cette ligne de facture" Command="{Binding ValidateCommand}"
             Clicked="OnValidateClicked"></Button>
diff --git a/BookAStar/BookAStar/Pages/EditBillingLinePage.xaml.cs b/BookAStar/BookAStar/Pages/EditBillingLinePage.xaml.cs
index d3678002..2a1d9f3d 100644
--- a/BookAStar/BookAStar/Pages/EditBillingLinePage.xaml.cs
+++ b/BookAStar/BookAStar/Pages/EditBillingLinePage.xaml.cs
@@ -1,5 +1,10 @@
 using BookAStar.ViewModels;
 using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using System.Windows.Input;
 using Xamarin.Forms;
 
 namespace BookAStar.Pages
@@ -10,11 +15,10 @@ namespace BookAStar.Pages
         {
             BindingContext = model;
             InitializeComponent();
-        }
-
+        } 
         public void OnValidateClicked (object sender, EventArgs e)
         {
-            this.Navigation.PopAsync();
+            OnBackButtonPressed();
         }
     }
 }
diff --git a/BookAStar/BookAStar/ViewModels/BillingLineViewModel.cs b/BookAStar/BookAStar/ViewModels/BillingLineViewModel.cs
index 102da3a8..61679112 100644
--- a/BookAStar/BookAStar/ViewModels/BillingLineViewModel.cs
+++ b/BookAStar/BookAStar/ViewModels/BillingLineViewModel.cs
@@ -58,6 +58,7 @@ namespace BookAStar.ViewModels
             {
                 SetProperty<decimal>(ref unitaryCost, value, "UnitaryCost");
                 data.UnitaryCost = value;
+                UnitaryCostText = value.ToString(unitCostFormat, CultureInfo.InvariantCulture);
             }
         }
         protected int durationValue;
@@ -106,9 +107,20 @@ namespace BookAStar.ViewModels
 
             set
             {
+                if (unitaryCostText != value)
+                {
+                    try
+                    {
+                        data.UnitaryCost = decimal.Parse(value, CultureInfo.InvariantCulture);
+                    }
+                    catch (Exception)
+                    {
+                        // TODO Error model
+                        // UI should shoud entry as wearing a wrong value
+                        // thanks to its `Behaviors`
+                    }
+                }
                 SetProperty<string>(ref unitaryCostText, value, "UnitaryCostText");
-                // TODO update behavior
-
             }
         }
         bool invalidCost;