i was parked in the local shopping centre's multi storey car park yesterday, when i got back to the car there was a big dent in one side of my roof

. looks like someones thumped it. also a few weeks ago a tile fell off of the garage roof onto my roof..not having the best of luck with the roof at the
mo 
sgt pepper is currently at the body shop getting the tile damage fixed.. can anyone reccomend a good dent removal technique/company in hertfordshire? thanks