I had the Apple (which is bigger) and a Renault Clio (similar size to Corsa?) and the chassis did fit at a push - if you took a wheel off it would lie flat or would sit on its side if not. Not much room for anything else in the boot at the same time though.
dont buy one, it will mess up and they wont give a f*ck
infact pay me postage and i'll send you mine, its has been used intotal for 6 months and every part of it has been replaced once (some at my expense) and it is now still broken and i have given up on it and it is sitting in the shed as i cant bear to throw it away as was so ££££
if you think im being overdramatic check out online review
If you're anywhere near Peterborough, I cannot recommend a trip to Kidicare highly enough. They've got a whole floor of prams and buggies for you to take a look at and push about - and, this is the best bit - will check to see if they fit in the boot of your car for you. Although if you smile enough, I'm sure that most shops would do the same - especially it it means making that all important sale.
I have the cherry and it fits fine in my Astra. Similar size to a Corse I think. I think you have been unlucky littleducks and if it were me I would be demanding a replacement by now. I have had no problems with my cherry and DS is 10.5mth now.