Phil, I finished most of that site from Digesters, DeWatering to TPR, all been fully upgraded from controllers to Scada screens, all replaced with S7-416 with Profibus-DP/PA & ASI Bus architecture with fully remote system control capability, even valves were Profibus-DP type with 0%-100% open/close control and feedback. VSDs you mentioned were probably the old ones as all new gear were with full replacement warranty but offcourse there is a pricy critical spare parts list to keep the plant running without need of a part. Anyway, my word is not to defend myself or Siemens rather to mention what has been done so far. But, as you said, some of their contractors as we call the three man band, does the job wyhout any proper insurance and when something needs to be changed, here the catch all the way ripping off.