Apple ID constant errors: can't change country or update payment

Hey guys!

So I've literally been struggling for the past few months with my Apple ID. One day the payment method just stopped working - which is okay and might happen, but then I can't find a way to fix it. First of all, I cannot update my payment method, and I've tried all possible options - all my bank cards, paypal and phone. It never works, there's always some error. Meanwhile, my cards work just fine for other services (Spotify, Netflix).

I started thinking that the issue is my country on the profile - it is set as the UK, but I'm not in the UK anymore. I want to change it, but yet again, I can't. I've checked it - I don't have any subscriptions left or anything left to pay for (the purchases are all paid), I've read the FAQ so many freaking times and I took all the steps.

And yet. My Apple ID does not function at all - I cannot use the App Store, I cannot update my country or payment, I cannot do anything.

It says that I cannot change the country at this time (been saying that for months) and all of my payment methods cannot be authorised for some reason.

At this point I'm just desperate. Any idea what to do or has anyone experienced the same?

Thanks guys, any help would be appreciated.