Not receiving calls

In October 2021 My Business phone stopped receiving calls from certain numbers, some of them contacts and some not saved on my phone. I've been to Vodaworld 4 times. We confirmed that it is not the phone, we changed to a different phone to test, and only certain numbers. They are not blocked. I've talked to three different customer service consultants and they keep on saying that it is not fixed yet. I am currently losing business and are considering to move the entire Company account to a different service provider.

The ref numbers is attached.