Elite Mobile / Vodacom..........BAD BAD BAD

I have submitted a problem, regarding a voucher that I were promised but did not get. They contacted me on Friday 02/07/2021 at about 14h30 and gave me a code which i was supposed to enter on a website. I tried to do that several times but it kept telling me the code is invalid. I tried to phone them back on the number ***) that they phoned me on Friday and it said that the number does not exists. So that leave me back to square 1.