Tuff Shed

I live in a community with a very strict HOA. I initialy went to purchase a 8x12 ft shed but told the Tuff Shed sales rep Michael Almaraz about the restrictions and was waiting for approval from HOA. I was told I needed to leave card on file to pay the initial 1/2 portion of price for 8x12ft Tuff Shed, so they could start with the process, which I did. I told them to make sure they did not make any more charges on my card without consulting me first. They assured me that would not happen. They told me they would wait on the size approval by the HOA before charging me the other half. Well, the HOA approved a 8x10 ft shed and not a 8x12 ft. I called to tell them but first, I checked my bank statement to make sure no charges had been made, only to find out they had already charged me for the 8x12 ft without my consent. I called sales rep. Michael Almaraz and he said he did not know any thing about it but he would check on it. I went to their sales office and I was told I would get the difference in price between the 8x12 ft and 8x10 ft. Michael said I would get a credit back on my card in a couple of week. So I left thinking things were settled. A couple of months passed and nothing showed up. I called Michael and he said to wait a few more months because it was at corporate level but he assured me I would get my refund. I paid $2820.45 total, charge for a 8x12 ft Tuff Shed but have a 8x10 ft Tuff Shed. Every time I call, I get told it is at corporate level. It has been a year and I still have not received the diffrence. It is my money. They have charged me for a product they did not deliver. They have failed to correct this mistake. They should be charged late fee's for each month they have failed to return my money. They have taken a year. All they keep saying it is at corporate level. I want my money back and I want it now. So what else do I need to do to get this to happen.