No phone, but I'm. Paying for it

I bought a phone through account store, I lost the phone since it was insured, I claimed for another phone which insurance approved my claim, when I got to the store they said I must pay shortfall of R1500 which I did, I waited one month, then the store told me that it was out of stock their supplier does not have it, they can offer me another one, which IL have to pay extra 500,which I did, their system even showed there's 22 available phones, then I waited a month again today they phoned me n said it's out of stock, I'm like how because I paid it how can it be out of stock, the lady says ppl bought them as it was black Friday.