Sorted the problem out..
The solution is to move all the validators to the last step of the wizard.
here is my code as an example:
<asp:WizardStep ID="WizardStep4" runat="server" Title="Step 4 - Finalize booking">
<h2>Finish</h2>
<asp:ValidationSummary ID="ValidationSummary1" runat="server" HeaderText="Errors"/>
<asp:RequiredFieldValidator runat="server" ID="RequiredFieldValidator7" ErrorMessage="Customer ID required" ControlToValidate="txtUserID" Font-Bold="true" ForeColor="Red" Display="None"></asp:RequiredFieldValidator><br />
<asp:RequiredFieldValidator ID="RequiredFieldValidator8" runat="server" ErrorMessage="Customer first name required" ControlToValidate="txtUserFName" Font-Bold="true" ForeColor="Red" Display="None"></asp:RequiredFieldValidator><br />
<asp:RequiredFieldValidator ID="RequiredFieldValidator9" runat="server" ErrorMessage="Customer last name required" ControlToValidate="txtUserSurname" Font-Bold="true" ForeColor="Red" Display="None"></asp:RequiredFieldValidator><br />
<asp:RequiredFieldValidator ID="RequiredFieldValidator10" runat="server" ErrorMessage="Customer address required" ControlToValidate="txtUserAddress" Font-Bold="true" ForeColor="Red" Display="None"></asp:RequiredFieldValidator><br />
<asp:RequiredFieldValidator ID="RequiredFieldValidator11" runat="server" ErrorMessage="Customer city required" ControlToValidate="txtUserCity" Font-Bold="true" ForeColor="Red" Display="None"></asp:RequiredFieldValidator><br />
<asp:RegularExpressionValidator ID="RegularExpressionValidator2" runat="server" ErrorMessage="Email format is incorrect" ControlToValidate="txtUserEmail" ValidationExpression=".+@.+" Font-Bold="true" ForeColor="Red" Display="None"></asp:RegularExpressionValidator><br />
<asp:RequiredFieldValidator ID="RequiredFieldValidator12" runat="server" ErrorMessage="Contact number incorrect" ControlToValidate="txtContactNo" Font-Bold="true" ForeColor="Red" Display="None"></asp:RequiredFieldValidator>
<asp:RequiredFieldValidator ID="RequiredFieldValidator13" runat="server" ErrorMessage="Enter number of people for booking" Font-Bold="true" ForeColor="Red" ControlToValidate="txtNoOfPeople" Display="None"></asp:RequiredFieldValidator>
</asp:WizardStep>