Breach of Advertised product by MTN

I went into the MTN Canal Walk store to upgrade my 2 contracts. The contract I chose came with an HONOR phone, a HONOR Tablet, and a R500 PnP voucher. The consultant told me that stock on the HONOR tablet is low and would have to wait for stock to arrive. The tab arrived a few days later. When went in store to collect, I was told they could not give me the R500 PnP voucher as the deal has expired, which is not my fault, but the fault of MTN as they didn't keep stock of the product at hand.

Shame on you MTN for going back on your word, on an advertised product.