Does SA stand for Saarland or Saxony? (SL or SN would be the official country codes - but I don't want to be a smartass here, I had to google it myself)
Presumably it means Saxony-Anhalt (which would be ST) - or?
Maybe one could also pursue a strategy that the profit, which in my opinion is reported far too high, might already be a break-even or loss if the construction project were realized today.
Or you go even further: You challenge the termination by the company and insist on building in the future at the agreed price. Take a cheap plot, have a house built, sell the house. That is definitely cheaper than €60,000.