That is appalling.  

Please complain to Canon  themselves that service franchise is not worthy of calling themselves a service centre, or be involved in any customer focused business. !!!

They are talking total bll**s !

If it is dirt it can be cleaned. The worst case scenario is they would have to remove the anti aliasing filter to clean it - still not the price of a new sensor or camera.

The only part of advice I agree with is not to buy Canon again if it meant dealing with such an incompetent service centre .

And every one said, 'If we only live,
We too will go to sea in a Sieve,---
To the hills of the Chankly Bore!'
Far and few, far and few, Are the lands where the Jumblies live;
Their heads are green, and their hands are blue, And they went to sea in a Sieve.

Edward Lear
http://www.nonsenselit.org/Lear/ns/jumblies.html