Ive given up on the grey square calibration test. I find it doesnt work very well. Instead Ive been just printing out a square of color and adjusting based on that. Seems to work better.
The banding problem i was having seemed to be due to not printing in high resolution (so they say). Basically I was printing on to canvas, using the manufacture's
profile, but printing in standard quality as they look perfectly fine accept that sometimes for no reason there will be an area of about an inch and a half where the color is faded and very bandy looking(through all colors). At first it seemed it was only black, whcih is why i thought it might have had something to do with the missing dots in the calibration test squares. But now I find that it happens in all colors, its just more noticable in darker ones. The supplier said to not use the profile provided by them and to just use a generic one but on high quality. Seems to work better, accept that its harded to get the right colors when using a non specific profile... and high quality takes much longer to print (and on canvas i really dont see the difference)
So pretty much my problem has been solved I suppose. I hope this will help someone else who may be in my situation.