Not able to buy at all

Try using a VPN on your phone when buying. It might not work , but give it a try. The issue could be with your bank too. Check there are no geographical restrictions on your card. Another thing is to go to your phone apps in settings, find the Meta Horizon app and clear the cache, this can solve problems, but don't clear the data. If you can't even change a credit card no, sounds like an app problem. Check the permissions in the app too, make sure camera, files, location ,  microphone and nearby devices are all allowed. Final solution is to uninstall the app and reinstall, though you'll have to go through the pairing process again. I hope you find a solution.

Hi ari.frei​ 🙂

In addition to what Maccyb123​  said....

You can try buying from pc store instead of using the phone app.
I don't think it'll makes a difference, but who knows.....

Shop Meta Quest VR games, apps, deals and more | Meta Quest | Meta Store

Issues like that could be account related. In that case you'll need contact support, so they can look into that.

Get support | Meta Store

Some useres found a workaround by creating a second Meta account and gift games with that account to their main account. 
Surprisingly, this often works....with the same payment method/credit card that does not work with the main account.😂

Maccyb123 wrote:

..... though you'll have to go through the pairing process again

Maccyb123​ I'm not sure about that....I can't remember, that I had to pair the headsets again after I uninstalled/reinstalled the app a few years ago.🤔..... might have changed...