Help with car hire - from southampton dock

[peanut1967]

Hoping for a bit of help finding a good car hire rate - best I have at the moment is £339 for a compact. This is from Southampton - my aunty and uncle are comming of a cruise visiting from Aussie - 17th June early morning returning the car at stansford London Airport 2nd July 5.30 pm ish - any help would be great

Angie