I cant stress too much the importance of having a quality insurer, on your side when it comes to defending a liability claim. When it comes to quality, near to the top of most peoples list would be Hiscox.
They really are experts in the arena of professional negligence claims and often can provide a pro-active approach to claims.
Where a customer is refusing to pay a bill and by pursuing a claim for this debt is likely to encourage a counter claim for professional negligence from the customer, they can potentially meet the unpaid bill rather than deal with a more expensive contentious claim.
Once they do get involved, they have an expert legal team working to defend your position.
Watch the video below which explains what happened when one of their Marketing clients found themselves in just such a position.