Find the Serial Number of your printer - if you lift the flap up it will probably be at the back but clearly visible.
They will identify the problem for you - it could be Printhead although non-Canon refills can also cause a problem - I know I've been there.
My problem stopped when I put a completely new batch of Canon original refills in - because my printer wasn't a year old they sent me a new printhead. They can recommend repairers but if so a new printer is invariably the cheapest option!
Hope this helps - would have given you Canon phone no. but decorating/disorganised!!