Cell C advertising what they cannot deliver.

I tried to upgrade my contract but Cell C did not have the phone they advertised. MTN and Vodacom had the phone on a similar package. My issue because Cell C does not have stock I now have to apply to have my no put on a pay as you go option to keep my no if I apply for the contract with Vodacom or MTN. The problem though is I now have to wait 30 days due to Cell C's incompetence to deliver what they advertise. Just well not their problem