With email and text communication being the first line of defense, sometimes implementation professionals rely too heavily on this way of communicating. When things are getting misunderstood or a client is escalating, I am always surprised how just exchanging words over the phone calms them down. I also find it helpful because it takes away the anonymity/delayed feedback of email, where clients tend to be more forceful. 

Not only do you get a quicker resolve, you maintain the relationship. Nevertheless, always a good idea to follow up in written communication, what was discussed over the phone for documentation purposes.