What size wall bolts for fixing a Sky dish to a hollow block wall

Lads,

Any recommendations on this? Mounting dishes on back garden wall hollow concrete blocks, what size and what type, as I have used for 80cm dishes thoses rawl bolts that are brass like and expand inside the wall but I found that sometimes when you take out the bolt a piece falls into the wall cavity making it useless to use again! How about the plastic rawl anchor that u screw a bolt into are they solid enough?

Thanks