Misleading deals

A consultant from YelloData called me on the 09.10.2017 in the afternoon and said my contract number was selected as one of the numbers to get a discount on my data usage. My call was forwarded to another consultant to confirm my details and bank details. I then told then I wasnt interested if I have to pay for anything. They confirmed it was for free as I was an old MTN customer. This morning I got 6 emails confirming from different companies confirming services with them and my debit order date. When I called those companies none of their numbers were working. YelloData is a big scheme and MTN is part of it.