I doubt that Safaricom is to blame for sending the wrong message to someone in your address book - the odds do not add up. What I know is that on smartphones, people usually commit the error of selecting a different contact when composing a message, due to myriad of causes

autosuggestion
screen delay, eg where you type pet, it shows Peter, then you type r it takes time to bring up Petro, you hit select, and the meesage goes to petro and not to peter