He's paid you holiday that you hadn't yet accrued and is now deducting that not accrued but already paid holiday from your last paycheck. That's how it appears. By all means, give him the money back and then ask him to pay you the full amount he owes you. Don't be surprised if you don't end up any better off though once the tax man has their share on a bigger lump sum...
If you've got 12.5 days holiday, that sounds like 6 months worth. If you have not used more than accrued then he can't just deduct money from you. Speak to CAB, put it in writing what your side is. The main thing is that he's asked you to work without pay, you need to officially rejected that option. If once you finish and CAB agree that you've been underpaid, then get a small claim going.
Might be an idea for you to do some mathematics, BM. We don't know the ins and outs of the maths do we. We just have a snippet or two. But from those snippets... It looks as though you had 22 days off in total that you were paid for and had 12.5 days actual accrued holiday. He claims you owe him two weeks and based on the above that looks about fair.
Can't understand someone paying you for holidays instead of sick pay. Get some advice from CAB or a solicitor.. BTW, to take him to a employment tribunal will cost you money, but if you're successful, your ex, employer will have to pay these costs.
Absolutely - get some proper advice - CAB will do; I understand they have specialists in that area. You either have a case or you don't. I personally don't have any knowledge on this that can help.
Not sure about the legalities of this so seek out CAB advice. Did a bit of googling: Statutory Sick Pay If you don't have a company scheme, you will be paid Statutory Sick Pay (SSP) by your employer, as long as you qualify. SSP doesn't start until the fourth day that you're off sick, so you might not get paid anything for the first three days. So...if you only have SSP and you're sick but your employer paid you during this time, then I can see they have a case for reclaiming this money (although how that stacks up legally I'm not sure as they paid you for time off sick when they shouldn't have). But I can see this might be why your employer is now counting these days as holiday i.e. in order to reclaim this money.
At face value it makes sense to me and legal technicalities aside seems quite reasonable... I've known quite a few who use holiday days when off sick, SSP isn't much and doubt many can easily cover missing a week or whatever wage - so rather than take that hit they just lose some of their paid leave. The problem it seems for the op is that he's only half way the year, used his full years holiday allowance but not going to be working a full year - in that sense I can see why the boss wants either two weeks work or some wages holding back as the op has received holiday days / pay on the assumption he'd be with the company all year. Dare say the sensible thing is for the op to have a chat with the boss, get the explanation and figures on paper and go from there - it's possible however vague the op may have asked / allowed the boss to use their holiday days to cover sickness, and in turn the boss thought they were doing the op a good thing as it allowed for him to still take home a wage for those days.
Good post gluggy. And in opting to pay holiday pay for those periods of sick leave....it seems that the OP's boss paid them. Saying you hadn't given permission to be paid does nothing to change the fact that you were paid. That you took the money. It's just a matter of do the maths add up? If they do then it's a zero sum deal. If they don't, that's a different matter.