Invoice received two years in arrears by Lancet

Unacceptable service from Lancet Laboratories. I have received a statement for a test conducted almost two years ago! No explanation on why I'm getting this statement now and no apology for their mistakes. It's unacceptable to expect clients to pay for bills two years later due to your inefficiencies in your administrative processes. Please acknowledge your responsibilities if invoicing was not done by Lancet due to clear lack in your administrative process. Very poor demonstration of customer service by Lancet.