Dishonesty

I bought a part in August 2020 and advised the person by the counter the details of my vehicle they gave me the part and assured me it was the correct one and if it wasn't if I returned it with tge receipt unused I will recieved a refund. I returned the part an wasn't given back paoerwork. But was told it needed to be checked. I waited 2 Weekes wit no word. When I called a month back I was told by Alex at the front desk that will refund me at the end of October 2020 the amount of R500 although I paid R900. It's now mid November I call him today he said money is been raised and we must remind him and he may come up WI about R700. They seems to be some dishonesty going on here.