Depends on how much you wish to accommodate this customer.
If ‘their’ customer broke the chain thru misuse, that’s your
customer’s problem. If your customer requested light delicate chains
then you fulfilled their request, you are not responsible after that.
They specified, you obliged.
BUT, look at what your cost will be to repair/replace the chain. If
its minor and you want to get repeat business you might consider
making the accommodation.
As far as their duty to pay, there is no question, they affirmed
they were satisfied with the order, they need to pay. They have no
basis to refuse to pay for the whole order. If it ever became a
proceeding, your willingness to swap a chain would be to your
What you ‘could’ do, is agree to replace the chains after you get
them back…simply drag your feet until you receive payment and it