rights of car can someone take a car registered in your name?

[mews]

i have been driving for a friend whos son has payed for he car and insurance on the understanding that i drive for them and i get to use the car, but they have made my life hell and i was running everywhere for them and had to drop everything and go when called, i have had enuff but now they want car back because i wont do anymore for them the car is in my name and i am the policy holder for insurance they are threatening to go to police do they have any rights? i need the car till end of month and will then give it back but can they just take it without my consent? i am the full drivers liecense holder