Adjusting salt, rinse aid hasn't stopped my dishwasher leaving gles & plates cloudy. Is it bust?

15 year old Miele dishwasher was brilliant until a year ago. It now leaves plates, gles cutlery cloudy blue. I have endlessly adjusted all the settings to no avail. Could the ion exchange resin in the water softener be the problem? Is it time to buy another dishwasher? I am reluctant to call a repair man who could take ages to tell me its bust. Any ideas?