Voicemail on O2

[MartinP]

I want to ask 2 questions about Voicemail and O2.

1) I want a visual notification of voicemail messages on my phone - a Samsung S20 but cannot find how to do it. If it is not possible that leads me to 

2) How do I disable voicemail on my phone?

I am missing crucial messages because I cannot see there are messages for me, apart from a tiny symbol in the notification bar at the top of the phone.

I wanted to speak to O2 customer services but that all seems to have been withdrawn in favour of a chat bot.

[Bambino]

@MartinP See if anything in this guide helps: All you need to know about O2 Voicemail 901. - O2 Community

If not: How to find help & contact O2: A Guide - O2 Community