Problems with second hand camera!

[Simons]

Hey

Im fairly new to photography but recently bought a second hand Canon 40D from a shop in Manchester a couple of days ago. But all of my images, no matter what lens are on the camera have these three marks on them.

this is a picture of a completely clear sky:

http://img36.imageshack.us/img36/9607/img074001.jpg

But as you can see from the image there are multiple marks. 2 of which are very bad.

Is there any way that i can fix this from home without taking it back?
And will they even take it back? It came with a 30 day warranty.

Any help much appreciated!

 

[PhotoXopher]

You have a dirty sensor, bring it in and have it cleaned - happens to everyone at some point in time.

There are kits to do it yourself as well, if you feel comfortable going that route.

 

[Simons]

You have a dirty sensor, bring it in and have it cleaned - happens to everyone at some point in time.

There are kits to do it yourself as well, if you feel comfortable going that route.

Thanks, i think i'll leave it to them though this time