Apple India — IPhone XR issues

Address: House no 941 sector 46 gurgaon

Purchased I phone XR on 29th dec last year.. it’s been 7months of me dealing with their Customer Care.. gave my phone to the IPhone repair centre as well but problem still persists.
Tired of installing and uninstalling apps. Audio msg from wats app don’t play on speaker.. this is intermittent issue.. while you are talking over the phone songs from YouTube or any music app starts to play. Even when u are operating phone.. any entertainment app will start on its own. I have restored the settings multiple times and updated the version (the most cliche excuse) as per Customer Care’s instruction but nothing seem to have worked. I need help.