Tbh fella,modern coilsprings are a huge problem,my aunties 325ci's had them done 3 times in the last four mots,all snapped by the pigtail end.

I think you'll be very unlikely to recieve any sort of refund as in all honesty their typical faults of any car.the logbook thing is odd though,of course the Dvla wouldn't accept a photocopy,youd be better off applying direct.