buliej, we took DS to Canada when he was 10 weeks old. We had requested the bassinet on the plane but didn't get it (some airlines allocate specific seats at the time of booking the ticket so just make sure you check with the airline if you do want it) so DS was in our arms the entire time which was actually okay (it's a 15hr flight to Vancouver...!). My SIL borrowed a capsule for half of our trip and we also hired cars with a car seat. I think it was about $10 extra per day but we certainly didn't have any trouble getting one, and they were all fine (we hired a car/seat on 4 separate occasions).

Can I ask why you have been advised not to rely on car seats supplied by car rental companies?