If your phone is showing SOS service, it means it's connecting to some network. For example, typically, when my T-Mobile 8220 shows SOS only, it's connecting to AT&T but can't find T-Mobile.
If you go to Mobile Network Options from the Manage Connections icon, you will be able to see what network it's connecting to. Also, check what your Network Selection Mode is. If it's set to Manual and the wrong network is selected, you'll never get more than an emergency connection. If you select Manual and let the phone scan for available connections, you will see if the Bell network is one of them. If it is, select it and see what happens. If it works, don't forget to put the network selection back to automatic, so that you will preserve the possibility of getting SOS when the Bell network isn't available.
P.S. According to Bell Canada, your phone doesn't need to have HSPA+ technology to access its network, only to "be HSPA (or UMTS) and 850 MHz and 1900 MHz compatible." (See Will my mobile phone or smartphone work on the Bell network?.) According to the product specs (for the 8220—I assume the reference to an 8820 in the subject line is a typo), your phone is GSM 850/900/1800/1900MHz. You just won't be able to utilize the HSPA+ download speeds.