Reader Matthew just cut his Comcast bill in half with a single phone call. He received a flier from one of Comcast’s competitors that boasted a much better price than the $175 per month he was paying. When he called Comcast and told them about the better rate, he was swiftly transferred to “customer retention” which must be a place of magical wonderment because by the time he got off the phone his Comcast bill had been reduced by $90. How did he do it? His letter, inside…