Information to supply when claiming late payment charges

Hello, We have sent a letter to a customer for late payment charges including details such as original invoice amount, invoice number, date of invoice etc. The customer has said we should have also supplied a copy of the original invoice so until they have that they will not review our claim. So I know for next time are they right? I tried reading the late payment Act and it does not really seem to say what should be included. The 'User guide to late payment legislation' on the BIS website has a lot more detail, and would suggest what I supplied was sufficient, however I am not sure where the information is derived from if its not in the Act. Of course the BIS is a government body.
So I have 2 questions 1) Do I need to include the original invoice with a claim 2) Is the User Guide considered the official word on how to interpret the act? Thanks. S

Simon,

Have a quick look at the Legal Warning to be found on page 5 of the Users Guide namely "...has been prepared to provide general guidance only"

The same applies to your "suggestion" that as a Government Body comments by BIS can be acted on. Whilst mucg in the Late Payment Guide is useful belts and bracestype of suggestions remember back to the Legal Warning...general guidance only and take your own advice.

As far as needing to supply a copy of the original invoice that looks like a play for time no doubt to be followed by others, watch out for there was a problem with the goods and or services routine. That being said why not send it along with the claim. It might just speed matters along.

Let us know how things progress.

In the normal course of events, before claiming a late payment charge, you have most likely already sent the customer the original invoice, probably also a statement and generally also an overdue payment reminder.
If the customer has not queried any of these, it is pretty poor of the customer to suddenly demand a copy of the original invoice when you claim late payment charges. So I would suggest it is just typical 'delaying tactics'.
However, the Courts also take a dim view of anyone making a legal claim where they cannot prove that they have made every reasonable attempt to ask the customer to pay and, in particular, warn them that failure to pay will lead to legal action.
I don't think it is in anyway 'necessary' to include a copy of the original invoice when making late payment charges in respect of it, but it will help your proof of having done everything reasonable that you could if the case proceeds to the courts.
The strange thing is that if you proceed to legal action to recover a debt, you will then find that the Courts will come up with no end of obstacles and fee charges to deter your attempts to recover the debt. This, despite the fact that these fees are paying for the process and the court staff wages, you will feel you are being treated as an irritant to their wish for an easy life.
Their attitude is basically that they consider you to be an idiot to have extended credit to anyone who subsequently hasn't paid you, and will then squeeze more money out of you (the idiot) for themselves. The supposed 'remedy in law' provided for you to recover the debt you are owed, is a sham. It doesn't really work and none of the politicians and the legal profession has any reason to change it. It suits them just the way it is.
You have to realise this Country is now built on the concept of everyone getting themselves into debt and the creditor being able to do very little about recovering what is owed to them. In fact debtors are often considered to be the 'victim' in so many cases.
I believe that small business is currently being severally damaged because of this attitude.