Late invoices - so they have to pay?

Hi all, wondering if anyone here can answer a question for me. Four years ago a friend of mine undertook some work for a company which was of an ongoing nature. She was to invoice every month and her business partner was to arrange this. A couple of months ago she dissolved her business with this man and discovered they had never been paid by the other company so she invoiced them the full amount. They have refused to pay her not just for the old stuff but for the ongoing business and are now disputing even the original rate agreed for this work. She no longer has a good relationship with her ex-partner however she checked with him and he said he invoiced this work at the beginning for about a year but couldn't get paid. However she has no proof of this. My question is are they legally obliged to pay going back that far or how would this work? Thanks for your help!!

Did she have a contract with the company?

It occurs to me to ask the questions: did she actually continue to do work for them after the partner could not get paid? Was no-one watching the income? Did no-one query non payment?

Technically, the debt may well be due but given the chaos that obviously prevailed I'd wonder if she could prove to a Court, if necessary, that she had done the work at all!

People are very very slow to pay even legitimate, properly incurred debts at the moment let alone pay out in situations like this.

mf

Another issue, is she invoicing under a different business name to the original?
If so any contract implicit or otherwise would probably be in default.
Furthermore, just my view, that if someone does not want to pay you, legitimate or otherwise, its very difficult to enforce here...

Hi all, thanks for replies. This was an arrangement for her to store documents. There was no contract as such but of course since she still has the files there is proof of the service. She is invoicing under the original company name as she kept this after her partnership was dissolved.