You can use Bancor by using MetaMask!
- Navigate to https://www.bancor.network/discover and choose to convert from tokens in Bancor to the token we want. In this case: POA20.
- On clicking "Convert", a pop-up screen such as below appears. Choose MetaMask
- Choose the amount of POA20 you want to buy or sell in the next screen and click Next.
- Finally, a MetaMask window will popup to confirm the transaction! After which you will have the amount of POA20 or ETH you wanted.