WhatsApp account hacking despite it being secured

I had a SIM card with a Sudanese number. It was linked to my personal WhatsApp account and also connected to an email. Then my WhatsApp account was hacked. I tried to enter the number in WhatsApp again and waited for the verification code on the SIM or email, but I did not receive any. I contacted the telecom company; they said there was no problem receiving messages on the SIM, but they did not solve the issue. Then I saw my hacked account on a new WhatsApp, as if someone bought my number from a fake number website and that it belongs to them now. They advised me not to contact them again or the new account would be hacked. I left it and did not find a solution. After about 3 months, the account disappeared. So I entered the hacked number in WhatsApp again, but I did not receive any verification message.