When I changed for this August (added an extra night) I received cahsback on my original reservation, there is no way of claiming for any extra nights you add on.
Thank you Wayneg, so I can change my reservation and still receive payment on my exisiting booking. I was worried that I may loose all out all together I didn't want to chance it.
I have had a Quidco account for years but only just started using it since Rpoints collapsed. With Rpoints and Disney it took 2 months from booking to being paid. My latest Disney booking with Quidco was done on the 30th Oct and changed to validated on 21st Dec, so hopefully about 2 months same as Rpoints used to take.