They have to notify you.
If they notify you & you don't respond, your problem.
If they notify you & you tell them that you don't agree, their problem.
Do you have an order from them?
Written or verbal?
I hate pricks like this & I really stick it to them.
I have one & one only invoice for $77 outstanding from January this year.
Big company, well known brand, they claim I didn't give them a 'Certificate of Currency' for my workers comp & public liability insurance so they aren't paying.
Their problem is that I have several expensive peices of their gear 'stored' somewhere til they pay up. :D
What is even better is just last weekend, they tried to log an urgent after hours call & I told them that they were on credit hold. The bloke on the phone was desparate & tried to pay by credit card & I said "Sorry, we don't take plastic." :cool: :D