No call back from SARS

I have been trying to get hold of SARS for a few months because I am unable to log on to my online app now I receives an email that I owe them for not submitting returns. I stay on the line for over 30 minutes only to get cut off the ended up getting a request for a callback, the gent called me but still cannot assist with my app he said he will log a call for me to be called back but till now there's no call but yet I owe them? How if I'm not even able to login to submit the tax return?