We are going to Spain with my mum in a couple of weeks, she has booked a hire car but her original booking did not include any car seats (we weren't planning to go with her). I asked her to add the seats onto her booking but she is grumbling about the extra cost and says Monarch just told her we should take our own seats. DC are aged 6 & 5 and have high-backed boosters - I didn't really want to take them on the plane because the back bit separates from the seat bit and I didn't want to lose half a car seat, or have them damaged by being thrown about. My mum also said that car hire seats might not be in the best condition. Are hire car company seats any good or do you normally take your own and are they OK in the hold?