verimark twister

after buying a Twister Pull chopper from your verimark store in GAME , the string snapped after 12 months , initially when i purchased it, i was advised of a 2 year guarantee, when i took it back to the store to return it (with the slip). i was advised by your salesperson that negligence caused the string to break ( can someone please explain the negligence part to me?!?!?!?) , after going back and forth with your sales agent , he only decided to replace the top part of the twister which he was clearly not happy with doing.its really sad because i've been a loyal customer of verimark over the last 12 years , i've bought numerous items from you which have done the job but sadly , i'll no more be supporting you guys going forward. will definitely try to look for alternatives to verimark