I've used this guy twice Spain to UK [including a very full bike box]. He charges 50 Euros door to door each way weather its a matchbox or something bigger. I can recommend. Call him on 0034 666782380.
Or our local free add runs an advert for Swift Transport also offering a Spain -UK - Spain service. Try 07857 484886 or swift.transport@rocketmail.com.
Oh, I've had good prices with "Parcel Monkey" too. Good luck.