Quote Originally Posted by mickello View Post
..... Unfortunately, they were unable to clean it as the dust was too 'gunky' and wouldn't come off. They certainly appeared a very professional outfit, and though they didn't charge me anything, it was pretty disappointing. Maybe I left it too long before getting it looked at? Ended up giving it to a friends son who was studying photography at school, and bought myself a new camera.
Unless you spray the sensor(filter) with some type of glue, this is not possible.
The problem is time. With these overgunked up sensors, it merely takes more time, and more clean attempts to get it clean. It's that simple.

I've had this, where I wasn't willing to do more than 10 sensor swipes(with the copperhill cleaning kit) in one sitting, and the dust wasn't too intrusive, as long as I didn't use too small aperture values.
I cloned out any really obvious bits.

As time wore on, I just took time to clean the sensor on a more regular basis, and after a few cleans, it came up clean again(D70s back then).

Also it must be said too, that when you 'clean the sensor', you don't actually clean the sensor itself! You are cleaning the filter that covers the sensor. Yep! there is a filter pack that sits over the sensor. The worst possible scenario is that if you had such a dirty sensor that wouldn't clean up at all.. they could have replaced the filter instead! .. Costly, but doable.
On a 400D, there are obvious costs considerations to ponder, but if any outfit claims that a sensor is too dirty to clean, I'd question their professionalism.
They should have at least explained any alternatives solutions available.
(I hope you didn't purchase this new camera from them!!)