Paid for a “diagnostic service” of my tire pressure sensor warning light. Driving my ML320 later the same day, the warning light returned. I went back to the office a few days later and was told, “ a new complete diagnostic would be required”. The new diagnostic would cost $395.00. That would be in addition to the original $190.00 I already paid,, without resolution. I actually determined the issue was the sensor frequency of the sensors was not compatible with my car. I thought that’s what a diagnostic service is for, to determine the problem and recommend a fix. PRs has not offered to refund or re-examine the car.