Right... You have the right to a new freewheel regardless of what they've done fella. Ask to speak to the manager, and inform him that while the freewheel was in their care you dont know what they've done, but they've clearly mashed it. Inform him that if you dont get either £70 to replace broken parts, or a new eno freewheel from them, you're well within your rights to get a refund from him at the small claims court. Inform him that you will win the case without problems as his staff have damaged your parts while under their care, and thus the shop will be responsible for both sets of legal fee's. Further to this, if you dont get a full refund, you'll be calling the local papers with details of your bad service while your parts were in their care. Does he really want all this for the sake of a £70 part, when his staff were clearly at fault... ? Should do the trick. Bike shops are insured for their workshop services, thats meant to be one of the reasons for taking a part to the 'professionals' for maintenance... backup should things go wrong. Any more advice pm me if need be...