ALDImobile nightmares in SA… anyone else?

I have had ALDImobile for a few years with no major issues (except in quite regional areas - but I’m rarely regional so I accepted that.) Lately, though, I have been finding that my phone data and cellular function have been really patchy in metro areas. It has been most noticeable in the hospital I work in. My phone will appear to have 4 or 5 bars of 4G signal, but randomly nothing (including internet/texts/phone calls/iMessage) will work for around 1-3 hours. No amount of phone reboots or network resetting will fix it. It just takes time. And the phone gets hot in this time, too. Suddenly, it will kick back into action with a flurry of missed calls and texts arriving at once. I have an iPhone 15 Pro that otherwise seems fairly robust and is up-to-date with its firmware. This has only just started happening in the last fortnight. I’m in SA. Does anyone have any ideas as to what might be happening? Has anyone else experienced this? It’s driving me insane. I’m contemplating switching providers - because I need my phone for work. Thanks in advance!