First thing: If you are ever having a problem with your internet the easiest thing to do is power cycle your modem and router. Turn the power off and unplug all wires from each device for 30 seconds, tthen reconnect the modem first and then your router. Shaw will tell you to do this when you call them, so trying it on your own can save you some time on the phone. Also, try bypassing your router, by plugging your computer directly into the modem, to see if the router is your problem.
Now for your specific issue:
Sounds like a packet loss issue. Could be several causes.
1. high network traffic - Caused by out of the ordinary usage, such as someone on your network ( known or unknown to you) downloading/torrenting massive files. Could also be the result of a virus/trojan/malware infecting your machine which is sending out spam etc. You should be able to diagnose and fix this yourself. You could use
Wireshark to see if the traffic on your internet is overly high.
2. Signal levels. This could be caused by a change in physical medium between your computer and the Shaw node/pedestal. Wires pinched, faulty connectors, interference on your wireless channel. To combat the wireless interference, you could switch to channels 1, 6 or 11( someone correct me if these are the wrong ones) which are the 3 available channels with the least overlap. It is possible your neighbour just put in a new router and it is on the same channel as yours, so try all 3 to see if one is best. For any other signal issue, call Shaw. They can probably diagnose the problem remotely, and send a tech out to fix if it is more than just power cycling your modem.