Complaints should always be done in person, never in someone’s back and never by texting.
You should never air your complain to others before speaking face to face with the person concern. The odds are that they will hear about it from a 3rd party. Who knows how that individual will have interpreted and repeated what you’ve said.
You shouldn’t complain by text because your recipient can’t hear your voice, they have no idea just how big a deal an issue is to you or if you are just pulling their leg.