Wammers has been keeping me informed of the situation through email.
My first impression is that all four sensors failing is unlikely as the possibility of even one EAS height sensor failing is usually remote. Usually, the common thread that would cause all four sensors to have bad readings is a wiring issue at the EAS computer C117 multi-plug. The general view in the repair world, is that EAS height sensors almost never fail but rather the wiring and more specifically the wire connectors are suspect. Additionally, a bad earth or a low vehicle battery can also cause strange readings with the EAS height sensors and other systems as well.
When there are problems with the EAS height sensors, it will usually throw an EAS Fault immediately. Although occasionally, if the sensor values are incorrect but still within the "normal" range of operation the EAS computer will perform a sort of decision algorithm or averaging.
I had a situation where I mounted my EAS Sensors incorrectly. This resulted in one sensor reporting incorrect but a height value that was still in the "normal" range of motion. The EAS computer would do its best to decide which sensor was reporting the correct value. The observable behavior was a sometimes normal height but then the height may change when driven. The rear would suddenly become much higher or lower than it should normally be. If I then requested a lower height and then asked the suspension to raise back up to normal height, the suspension would be level again for a period of time. It is clear that the EAS computer can try to cope with a bad sensor by either ignoring it or performing some sort of average on the sensor values.
It sounds like going with the repair shop is the most viable option, as they are currently in possession of your vehicle. Unfortunately if the only way to get your vehicle back home is a tow, then the repair shop may be your only option. Although I think this is a wiring/plug issue and not a EAS height sensor replacement issue. Depending on the vehicle history, this could also be a height sensor mounting issue, maybe the EAS sensor arms are backwards, was the vehicle ever in standing water, maybe a simple cleaning of the C117 multiplug or the height sensor plugs would resolve the issue.
There are several possibilities and my gut feeling is that the replacement option is the last resort. But then again, I have never seen the vehicle.
