Poor service.

I'm not happy with mtn seeing that if was advised earlier this year that I could qualify for an up grade in April 2020. My mtn app shows 18 of May 2020. I phone in yesterday and was advised that I could up grade an the constant would have came back to me with the phone I was looking for but she never phoned my back. Now this morning I was advised that I can only qualify in June for the up grade? It has almost been 2 days since I logged this complaint with them on their site and on Facebook and no reply from them as yet??? Please help.