diff --git a/.gitignore b/.gitignore
index 2cba99d87..e66b85740 100644
--- a/.gitignore
+++ b/.gitignore
@@ -4,4 +4,5 @@ lib
 .Python
 tests/
 .envrc
-__pycache__
\ No newline at end of file
+__pycache__
+*pyvenv.cfg
diff --git a/server.py b/server.py
index 4084baeac..be66cd328 100644
--- a/server.py
+++ b/server.py
@@ -41,14 +41,29 @@ def book(competition,club):
         return render_template('welcome.html', club=club, competitions=competitions)
 
 
-@app.route('/purchasePlaces',methods=['POST'])
+@app.route('/purchasePlaces', methods=['POST'])
 def purchasePlaces():
-    competition = [c for c in competitions if c['name'] == request.form['competition']][0]
-    club = [c for c in clubs if c['name'] == request.form['club']][0]
-    placesRequired = int(request.form['places'])
-    competition['numberOfPlaces'] = int(competition['numberOfPlaces'])-placesRequired
-    flash('Great-booking complete!')
-    return render_template('welcome.html', club=club, competitions=competitions)
+    competition = next(
+        (c for c in competitions if c['name'] == request.form['competition']),
+        None
+    )
+    club = next((c for c in clubs if c['name'] == request.form['club']), None)
+    places_required = int(request.form['places'])
+
+    if places_required > 12:
+        flash("You cannot book more than 12 places in a single competition.")
+        return render_template(
+            'welcome.html', club=club, competitions=competitions
+        ), 200
+
+    club['points'] = str(int(club['points']) - places_required)
+    competition['numberOfPlaces'] = str(
+        int(competition['numberOfPlaces']) - places_required
+    )
+    flash('Great - booking complete!')
+    return render_template(
+        'welcome.html', club=club, competitions=competitions
+        )
 
 
 # TODO: Add route for points display
@@ -56,4 +71,4 @@ def purchasePlaces():
 
 @app.route('/logout')
 def logout():
-    return redirect(url_for('index'))
\ No newline at end of file
+    return redirect(url_for('index'))
diff --git a/tests/unit/test_purchase_places.py b/tests/unit/test_purchase_places.py
new file mode 100644
index 000000000..c668efd55
--- /dev/null
+++ b/tests/unit/test_purchase_places.py
@@ -0,0 +1,48 @@
+import sys
+import os
+import pytest
+sys.path.insert(
+    0, os.path.abspath(
+        os.path.join(os.path.dirname(__file__), '../../')
+    )
+)
+
+from server import app, clubs, competitions # noqa
+
+
+@pytest.fixture
+def client():
+    app.config['TESTING'] = True
+    with app.test_client() as client:
+        yield client
+
+
+def test_purchase_places_exceeds_max_limit(client):
+    response = client.post('/purchasePlaces', data={
+        'competition': 'Spring Festival',
+        'club': 'Simply Lift',
+        'places': 13
+    })
+
+    assert b"You cannot book more than 12 places in a single competition." \
+           in response.data
+
+    competition = next(
+        c for c in competitions if c['name'] == 'Spring Festival'
+    )
+    assert competition['numberOfPlaces'] == "25"
+
+
+def test_purchase_places_within_max_limit(client):
+    response = client.post('/purchasePlaces', data={
+        'competition': 'Spring Festival',
+        'club': 'Simply Lift',
+        'places': 12
+    })
+
+    assert b"Great - booking complete!" in response.data
+
+    competition = next(
+        c for c in competitions if c['name'] == 'Spring Festival'
+    )
+    assert competition['numberOfPlaces'] == "13"