The PMI industry is becoming increasingly disturbed by the amount of incorrect invoices it receives for private medical treatment.
Treatment sourcing specialists Medical Care Direct (MCD)has highlighted the issue, having tracked the problem in detail over the past three months.
It said either overcharging or erroneous charges were the most common errors.
Jan Lawson, chairman of MCD said, "During August 11% of invoices received were wrong, in September it was 15% and October 14%.
"Most of these relate to fixed price procedures rather than normal itemised bills so you would think that the scope for error is small. But they are totalling over £20,000 each month, a significant sum.
"Our worry is if we as experts in treatment sourcing are experiencing these error rates what hope is there for an individual who arranges their treatment directly.
"This experience suggests there is a good probability of them being charged more than expected and/or getting a confusing bundle of bills."