Ford Ranger is a danger

My Ford Ranger 2018 model is at 47000 ks and started switching itself off whilst im driving at 40000 odd ks. Booked it in as its still under warranty and only in its 12th month and they said nothing was wrong. On Sunday I was coming out a turn and in the middle of the road whilst turning it just switched off, luckily for me they was no car coming from the right. I sent it in immediately and now they say I cant get a courtesy car to continue running my business. This is so unprofessional as they are not acknowledging they fault with their vehicle and keep saying they are diagnosing the car. I could have been driven into on Sunday than what would they have said? How can I resolve this?