Can you check your account details to see what plan you are on. Is it ADSL2+ or maybe "off-net"?
Look on the ADSL2+ coverage map on TPG home page (at bottom of page). Depending on just where you are in Croydon South, your local exchange may not have ADSL2+.
Croydon exchange has ADSL2+ but Bayswater North is only off-net.