@Nadim123 -- it is either a marketing ploy to get you to upgrade to a faster speed, a "bad" cable-modem (ask Shaw to replace it), or "bad" wires/connections (loose? kinked Ethernet/coaxial cables? failing coaxial splitter?) inside your home, or a "bad" coaxial line from your home to the nearest telephone pole.
If you never get over 100 Mbits/second, replace any "CAT-5" Ethernet cable by a "CAT-5e" or "CAT-6" cable.