hi
maybe your gear linkage is wearing out, its a common problem on the Corsa's, but i don't know what gears it affects you from selecting ,new ones are available on ebay (normally) - you didn't mention the year etc,
as for the handbrake the Corsa C has four cables, is it all limp like a cable has broken, or is it in a serious need of adjustment.
not that i'm a connoisseur of corsa's - tho i am on my third one & do handbrakes on a regular basis,
as for prices, all the cables should cost �20-�30 maybe if you go that route,
gear linkage from �35- �50
as for labour who knows -unless you diy
have fun.