i have recently purchased a used phil and ted explorer for my grandsons. I took it out with just one seat unit in and one of my grandsons but discovered when he fell asleep and I layed it flat he was totally exposed. is this normal or is there a back cover protector missing. I have searched the net with no look. also, I purchased a single raincover which supposedly was to fit both the explorer and navigator but on using it for the first time it falls short at the bottom and has Velcro where it seems there should be prestuds. To be honest I find it more confusing the more I read about how to get the best out of this pram. I have a grandson who has just gone 1 yrs old and another who is just 5 days old. any advise would be appreciated.