Deals and offers are only clickbait

Vodacom is running several summer contract deals at the moment. I app**** for a contract of R280 per month, great deal on the devices. I get a call explaining that due to the fact that I do not have a high credit score(I only have a car installment, no credit card or a bunch of store accounts by choice) I do not qualify for the deal, but I do qualify to get the specific device on a contract, which will cost R390 per month(providing me with minutes and data, not the flexi contract providing me with a set amount of airtime I can top up when required. Please explain how I do not qualify for a R280 per month contract but I do qualify for a R390 per month?