Pick N Pay Express, Heritage Street strand Dishonest & un ethical business people.

Pick n Pay Express, Heritage Street strand. Cape town. Dishonesty, we went and got a gas bottle about 2 weeks ago they told us we need to pay R 800 but we can bring it back they will give our deposit back. Less the gas. Today we went back to refill with the slip. And they came back to us saying the owner change their mind. How can a business such as pick n Pay be soo dishonest to try and get the sale i now sit with a empty gas bottle that cost me R 800. Its really ********* business,