Hi @adam44, I am sorry to hear about this.
Firstly, Do you have any case or a protective film mounted on the phone, and if so, have you tried removing it in order to make sure that there is nothing covering the loudspeaker? Also, have you been able to carry out a quick test of the loudspeaker in the support app in order to see whether the loudspeaker works as intended? In order to do this, Find and tap Settings > Support > Xperia tests > Media.
Another thing that you can try is to reboot your phone in safe mode to see if the loudspeaker works as intended there. All apps downloaded from Play Store is temporarily deactivated while in safe mode, and by doing this you can see whether this behaviour is caused by a downloaded app. For more information on safe mode and how to use it, click here.
If the loudspeaker behaves the same in safe mode, My suggestion is to repair the software on the phone using a computer and Xperia Companion. Keep in mind that a software repair will erase all user data from the phone, so it is advised to do a backup of your user data before proceeding with the repair.
Try these measures and let me know how it goes!
