No credit approval…with an 820 credit score

Yesterday my wife and I signed up for 2 mobile lines. The person in store stated that we qualified for the free year for 1 line promotion and we could trade in our phones for a discounted rate on a new phone. Upon “running our credit” AFTER he switched our lines over to their service already, he informed us we were not approved for any credit and therefore could not get the promotion. Our credit scores are 780 and 823 respectively. There is no reason that either of us should be denied credit. We have called customer service multiple times and they all tell us to “check with our bank”. We already have. Nothing is frozen, there are no late payments, we have never missed a payment. I’m really frustrated at anyone’s ability to reconcile this issue. Every person we talk to passes us off to another. This is a terrible first impression and I am incredibly frustrated.