Are you using Google messages? Under settings for Google messages, there's a setting that had auto download files that was set to off by default that might be to be set to a number. You can ask your carrier if your APN settings are correct since you're hot getting the media files they're sending. The settings in the Google messages, under RCS chats should have a send as SMS that should be toggled on. Try that. I use Google voice for texting I haven't used giggle messages much but read it's being forced on everyone. 
