We rented the car for 6 weeks! Never did that before but it worked. We struck it lucky and happened to get a brand-new car (7 miles on the odometer when we got it!) and that was a treat. No surprises on the price.
It took a long long time to sign up and to return the car, because we rented it for so long, 6 weeks. Both times the agent had to turn us over to a specialist agent, and I don't find that surprising, but both times the first agent struggled with the problem for a very long time before turning us over. Also had to move our 6 weeks' worth of luggage from first to second agent, far away in one case. The reason we had to deal with an agent on our return was that we switched credit cards -- that ought to be quick and easy, surely?