What should I do about this co-worker?

I work as a volunteer at a charity bookshop and there is this other guy who works there but he is a paid worker. He is so lazy, he does as little physical work as he can get away with. He spends most of the time 'propping up the till' or 'doing work on the computer'. The volunteers in the shop do more work than he does and they aren't paid anything! His contract is up for renewal but it is likely that he will end up being kept on as no one else has applied for the post.He is a nuisance, no one wants to work in the shop when it is his shift, wouldn't this be jeopardizing the smooth running of the store, if he is the only one there because no one can work with him?? Any suggestions? the manager knows about what he is like but he just kisses the regional manager's **** all the time when she is there so the store manager's hands are tied.