These sorts of issues are often related to a poor signal in your home or neighbourhood. Did the technician say that the signal was good? Here's a post on the topic. You can check the signal yourself using the link there, or you can call Rogers and have them check the signal remotely. Why was the technician there in the first place? Shortening a cable has almost no effect relative to other possible causes like a poor splitter or poor connection, etc. Perhaps he was just redoing the ends/connectors in case it was a poor connection. He should not have left if the channels were not coming in properly, or if the signal was poor.