Complaint

I layby an Arianna 6pc LS Black in November told the store I will pay it full in December. And Sunday I went to the shop to pay. And I was told the black I layby for is out of stock but they have the brown similar. I didn't like the brown at first but I was left with no choice but to take it anyway. They sent me an SMS yesterday the 21st of December saying they will deliver my 3pc Arianna brown. And I have paid in full for 6pc LS 😭😭

I contacted the guy who assisted me. He's now telling me that he checked I need to add money because with the brown I took it was a thousand less but even so they won't deliver Friday. Can someone help me because I had a reason to buy and the need to have them before Christmas.