Sounds like you have been ripped off Broonie (theiving barristers), did they leave you the bit of stanley blade?, after 1 day in the open the 'snapped edge' would be well rusted, I'd E-mail (that way they are stuck to putting stuff in writing) the company manager relating your story-if the puncture 'was in a bad place mate' then it shouldn't be repaired !, ask on the E-mail for your £20 back or your gonna post up this story on the half a dozen Bike forums that your a member of ,after you get a promise by E-mail of a £20 refund--- then ask for a credit note for a small (5%) discount for future tyre purchases or you will write a nice story in the half a dozen Bike forums you are a member of and will ALSO purchase your tyres from elsewhere-do all this in writing