Yes, you can.
This is best done via FTP. Please use your FTP platform you have installed on your computer.
Go to wp-content > plugins > WC-Payment-MPGS > images
There you will find a image called mastercard.png
Rename the original image and upload a new image with the name: mastercard.png
The size of the original image is 32 x 20px or 1.13 x 0.71 cm, l suggest keeping to a size similar to what we had used. A larger image may look a little odd.
If you update the plugin, you will need to repeat the process as the update will override the changes you made. At some point we will make this an option to select a image to suit your merchant account.