Horrible service from momentum

I've had my medical aid with Momentum since 2023 and I just recently changed jobs so I needed hence I needed to apply for membership but I still app**** for Momentum,on the 22/07/2025 I received an email confirmation of medical aid and there is no waiting period and the effective date was 01/07/2025. I was admitted and now my medical is refusing to pay stating my medical aid only started on the 01/08/2025 but the letter that was sent to me was stating 01/07/2025 when I emailed Momentum to query this they just sent a new letter which I had never received before.