I recently sent my S80 in for calibration. The process was simple. To encourage more people to obtain the calibration they should offer a dusount with an email reminder. The unit is of no use if it is not accurate.
The calibration was performed quickly and the device returned a few days sooner than I had expected, which was a relief because results had grown inconsistent and I rely on the device to ensure that I don't get into trouble with my ignition interlock device (the accuracy of which I have considerable less confidence in).,
The process was easy. My breathalyzer stopped working. I called BACtrack and the customer service rep determined that my unit needed to be re-set. Using their website, I was able to pre-pay for the service and get directions on sending it back. It took just under two weeks for it to ship from the East Coast to California, get it calibrated, and shipped back. It's just like new!
My 2nd S80. The first would not recalibrate. Possibly due to too much time between recalibrations so I will be more vigilant with this one. Also will try and be sure to use it more regularly in order to keep it accurate. That said, the unit is small, easy to use and assumeably accurate though I really don't see how the end user can verify short of testing it against a known quantity, say at the police station. I did have occasion to be roadside tested by the police and my unit registered .044. The officer's unit registered .066. Yikes! Too close for comfort. Excellent for a reference point but you are playing wth fire if you try to take it up to the threshold. That should not be the purpose for using this.
It took me a long time to finally part with the Bactrack mobile so that it could be calibrated. I was concerned about accuracy, but I also always liked having it available. Fortunately, service was extremely fast after the item arrived. Too my surprise, a new unit was sent since the old unit could not be properly calibrated. You won't find many companies out there who care this much about their customers. Spread the word.