As a new driver, you shouldn’t be doing 14 hour shifts. You could get tired and have an accident.
When I first started, I insisted that the agency gave me a driver’s mate. I just drove the truck and at every drop my driver’s mate did all the work. I also insisted on no more than 8 hours work.
On the second day, the company that the agency had sent me to tried to pull a fast one by telling me I was going out on my own that day. A quick phone call to the agency to let them know that I wasn’t going to do the rest of the week unless I had a driver’s mate soon put paid to that idea.
Admittedly it did help that the agency were really short of drivers that week as it was the summer holidays, but the moral of the story is that if you let an agency walk all over you they will.