Melon Mobile - problems?

I switched to Melon without any problems. But lately things are clearly going wrong there. I get no response from them when I contact them for support on their Whatsapp number - they are usually very good. Then my sister in law switched to Melon - on my recommendation. Well, it is now two weeks later and after she has paid. Her port from MTN was fine but they simply cannot activate the Melon sim. So for two weeks now she has not been able to access her banking app since she cannot receive any SMS. This is totally unacceptable