If the flat antenna doesn't work, you can try an antenna that has a reflector which will make the antenna more directional to reject interference from multipath reflections. An Antennas Direct Clearstream 1:
https://www.antennasdirect.com/store...V-antenna.html
Two BestBuy stores in London list it in stock:
1.North London
2.Across From Masonville Place
3.1735 Richmond St., Unit 1
4.London, ON, N5X 3Y2
5.Phone: (519) 963-8494
1.London
2.Across from White Oaks Mall
3.1080 Wellington Rd.
4.London, ON, N6E 1M2
5.Phone: (519) 686-2160
The Antennas Direct C2V might also work, but it is more expensive and has more gain than needed for you.
https://www.antennasdirect.com/store...-Complete.html
http://www.bestbuy.com/site/antennas...=1218809260470
UVSJ
http://www.solidsignal.com/pview.asp?p=uvsj
http://www.3starinc.com/pico-macom_u..._combiner.html
http://mjsales.net/products/tru-spec...ant=1198505857
Please let us know the results of your tests.