Corporate bullying

I have signed a contract for the Huawei Matebook D14 (what I assumed to be the Ryzen 7). I got told there was no stock and that I would be contacted when the stock arrived. A week later I got told to come collect the laptop. On arrival they told me the price of the contract went from R549 to R699. I did not and will not sign a new contract as I have signed one already. They are now saying that the new stock is different but at first they could not tell me what the difference was.

I signed for R549 and I would like my laptop now, it is not my fault if the wrong laptop was ordered. They had told me they ordered what I had paid for, but a different laptop came and that it's from Huawei's side. I didn't sign a contract with Huawei, I signed it with Vodacom.

They have now been trying to bully me into signing the more expensive contract. If there was no stock of what was advertised they should have waited for the new stock to arrive.