when we used to fly with the kids were young, it was a lot cheaper to get a couple of seats from Argos – planes will transport them free of charge, over and above the luggage allowance. They’ll even let you take them hand luggage.
They’ll be better quality than an old hire company one as well. Either leave them or bring them back and use them as a spare.
Last time we went to Portugal (albeit Lisbon) we used Enjoy, and eventually got a car from EPI through them. Got upgraded to a brand new Focus Estate, having paid for the level below.
Very relaxed – no complaints at all, and would use them again. There’s still a lot dirt tracks away from the main roads, so you don’t want a firm that’ll charge you for every stone chip