Rented a car, refused to give car when at airport and have not received my refund yet after many calls

They are complete ********. I rented a car for my son and they refused to give him the car because he had no credit score. No where is it claimed you need a credit score. I confirmed before my son flew that all would be good as he could have swiped his debit card for the excess and deposit of *** and would be credited again when he returned the car. They have not refunded me the money I paid to get the rental which they refused to give. They also put in a debit order to deduct *** a month for "prime" which I did not agree to. I will never even go into their site again even to check prices .... guaranteed to see debit orders again. STAY AWAY and DONT ENTER ANY INFORMATION!