The prints you had done at ASDA, were they done through a 'photo kiosk', ie via a touch screen and an instant printer?
If it was then it was a dye sublimation printer, and like as not a Sony, and if it was , it sounds like it is not being maintained properly.
There are many dye sub printers out there, from different manufacturers, they are not cheap, but if you are doing alot of print production , they are worth the investment.
There are two main catagories - rol feed machines to do sizes of 6x4, 7x5 and 6x9", and another category that do 10x8's, and 12x8's.