better error handling

rowers/views.py

@@ -29,6 +29,7 @@ import re
 import cgi
 from icalendar import Calendar, Event
 import rowers.braintreestuff as braintreestuff
+import rowers.payments as payments
 
 from django.shortcuts import render
 from django.template.loader import render_to_string
@@ -1074,6 +1075,10 @@ def paidplans_view(request):
 def billing_view(request):
     r = getrequestrower(request)
 
+    if payments.is_existing_customer(r):
+        url = reverse(upgrade_view)
+        return HttpResponseRedirect(url)
+
     if request.method == 'POST':
         billingaddressform = RowerBillingAddressForm(request.POST)
         planselectform = PlanSelectForm(request.POST,paymentprocessor='braintree')