Electrical water pump

On the 5th of May 2020, went to Border Irrigation Queenstown bought a pump and a tank, to my surprise when my plumber was connecting it to the tank, it didn't work and looked used and rusty. Took it back and was told that it was goint to be looked at and I will be called to come pick it up. So they took my number and promised to call. After a week with no call and I took the initiative to go back again and check them out. To my surprised they didn't even know which pump was mine. I was given the pump took it back home and called the plumber to come connect, again it didn't work. I have go back again tomorrow and take it back. I just want a new pump or my money back