Bit of a bugger this one, happend to us a few years ago, one and only time, but it causes allsorts of headaches for you, can i assume that this is daytime cleaning?
Is it not possible to change to out of hours cleaning, so your clients staff are not there?
If the above is not possible, could you not switch this cleaner to another site and change another cleaner to this site?
Legally, a minefield, if you have to lay him off completly, there is a chance he could sue for unfair or constructive dismissal, good luck!!
We always introduce our staff to our clients at the outset of any contract, we also train each staff member in customer service and behaviour whilst on our clients premises, this genreally works well, but as i said, this is really a no win situation.
Regards,
Rob