MTN charges out-of-bundle without my consent

On 26 April 2020 MTN started charging me Out-Of-Bundle rates when I had never opted in. As far as I know, the telecommunications companies are prohibited from charging customers the out-of-bundle rates unless such customers had opted-in. I never signed up to have mtn charging my airtime for data when my data runs out. I have 2 numbers with mtn and on 1 of these numbers the mtn App does not allow me to limit data usage while it does on the other number. I have tried to contact mtn regarding this but cannot get hold of customer care. I find this act by mtn to be in contravention of the ICASA End-User and Subscriber Service Charter regulations (as amended in 2016, regulation 8B(2)). This is what the regulations states " Where an end-user does not opt-in to out-of-bundle data charge as per regulation 8B(1)(c) above, a Licensee must not permit any out-of-bundle data usage by an end-user until such time that an end-user purchases new data bundles or opt-in to out-of-bundle usage. In the event that an end-user does not make an election, whether to opt-in or opt-out of out of bundle usage, the Licensee may either immediately terminate data services or continue to provide data services, provided that the provision of the service shall be on the same terms and conditions applicable under in-bundle usage"