Poor Service - Samsung Head Office and Exchanges

In Feb, I took my Samsung S21 Ultra in for repairs at my local repair centre as it randomly died whilst in an app, after about a week I was told that it can't be fixed and I need to get an exchange at a store as it was a manufacturing fault however I need to call the Head Office and get a Manger to Authorise the Credit for the Store Exchange.

I have been calling the Head Office non stop and spoke to a different consult every day and they all advised I would get a call back to Authorise the same, Apparently there is no Manager available to take my call whenever I call..... however ANOTHER WEEK Later and still nothing! No Call Back and I'm sitting without a device that I paid an arm and a leg for!

@Samsung - please can you Authorise the credit at the store so I can get a replacement device, I don't mind paying a cash difference for a better device that won't randomly die on me. I need a way forward here or my money back as this is ridiculous and approaching a month now.