Bad Customer Service by Cell-C

I went to Cell-C Brooklyn Mall outlet looking for a contract and a new phone. They assisted me to make a decision on a phone and committed that the phone under the package i was looking for is available. I submitted all the documentation required on the 15 May 2018 and they told me they will call me later to confirm the credit checks validation and affordability. At that time i asked them if they had the recommended phone on the package and they confirmed that they have the phone, we agreed on the phone and they even convinced me to take the available colour(Blue). Couple of hours later they called me to tell me that my application has been approved and I can come to collect the sim card for purpose of porting my number from MTN to Cell C and the phone can be collected the next day once porting is completed. During that call i even asked them if they have the phone and whether i can collect the phone the same day. They insisted that i cannot collect the phone until the porting of the number from MTN to CEll-C has been completed and reasons why i could not get the phone. They even confirmed the phone i app**** for and confirmed that they have it on stock. I confirmed that i will pick the sim card later in the day. I went to the store to sign the remainder of the documents and to collect the sim card. They insisted that i would only receive the phone the next day as i am porting my MTN number to cell-c. They started registering the phone on the system , at that point they told me that they can't give me the phone anymore as the promotion target has been met. I told them that they should have checked that, when they called me to collect the phone earlier and the only thing i want them to do is to honour their commitment. I indicated to them that they should have validated whether their promotion is still valid before they called me to come through to the store to collect the phone and they should honour their commitment. I was appalled when they asked me to take another phone which has a package more expensive than the one we agreed on earlier and they attitude the gentleman gave me when i told him they must honor their contract.. All i need is Cell-C and this store to do, is honour their commitment and promise.