Try not to panic, there are things that can be done! Firstly you need to review what contributions should have been made.
We also suggest you notify your professional advisor as they can give you specific advice to your situation.
Finally; make a voluntary disclosure to The Pension Regulator. They are there to help not to penalise for genuine mistakes that have happened.
If you need advice on this and some reassurance give Cheadles a call. Based in Stafford we can help go through the problems and find solutions to minimise if not remove all penalties that you could incur for not meeting your employer obligations on time.