Hand stitching to a Leather holster

I walked into the store and asked for a price on some hand sewing on my leather holster. They gave me a price of R45. I asked for a better price and was directed to another person who told me R25. I agreed and gave them the go ahead. When I came to collect they told me that they had not seen the work properly and they cannot charge me R25, the price is R45. I argued with them that we had an agreement but they simply couldnt understand. After much arguing, they said I must pay R35. I paid grudgingly and will never go back to that store ever again.