Third Party putting in car insurance claim after 6 months?

[Theonlyoneiknow]

We had an incident last year when DP reversed into another car which was stationary. There was hardly a scuff but we exchanged details and went on our way. Informed insurer and told him what happened and that as the damage was barely noticeable didnt expect to hear any more.

The third party did contact our insurer to also notify them but that was it. We then get a letter three months later saying that as no claim has been made the case has been closed.

Fast forward to now, six months later and we have received a letter from the third party solicitor (it was a company vehicle) advising us that we have to pay for the damage or go to court and that they have also sent a letter to our insurers!

As we have moved house we only got the letter today, 6 weeks after it was written (6 months after the incident).

We will call our (now old as have changed company) insurer tomorrow but I'm not sure what to do! The inspection report for the damage to the vehicle was done nearly six months after the incident and the amount they want is significantly higher than a barely visible scratch.

Any advice? Thanks in advance!