Keep Receiving Messages to Make Payments for a SARS Profile that is Not Mine

I have been receiving SMSs for months now demanding payment for overdue amounts relating to a SARS tax profile I do not own / am not associated with. I have emailed Nimble multiple times with the issue but no one has bothered to get back to me, at least not via email. I keep receiving demands for money owing, though; even though I am not the intended recipient. I would like this issue sorted out so that these debts are not associated with my name or number.