Unauthorised request to port cellphone number

I've been receiving SMSs from MTN these last 2 weeks on a daily basis that I've requested to port my cellphone number from Vodacom to MTN, which I haven't done!When phoning MTN call centre at ********** 667 on numerous occasions, they were unable to provide me with any detail on where these requests are coming from. When I requested them to block these requests as they were ********** I was told to first open a police case and then provide them with a case number. I am very concerned around customer verification within MTN as it is evident that they don't authenticate customers before acting on any requests