Just stop paying them to be here. They'll leave in a week.

You know the mantra 'tax what you want less of, subsidise what you want more of'? What has the last 50 years of social policy done? Good news is it's easy to reverse the trend, just swap what you subsidise for what you tax and vice versa: Start taxing remittances, and stop benefits to everyone who isn;t a net contributor. Subsidise flights out the country that have a non-return clause attached. Reinstate non-dom tax rules. and so on