This is the letter in excerpts:
You have concluded a consumer construction contract with our client for the construction of a single-family house ... at a price of 200k. The construction contract was not implemented, so our client set deadlines for you by letters dated ... and ... respectively for you to perform your cooperation obligations (designation of a building plot and proof of ownership). These deadlines have expired. You have not fulfilled your cooperation obligations.
According to §§ 643, 643 of the Construction Contract Act, the consumer construction contract is deemed terminated with the legal effects of termination for cause in favor of our client. Our client is entitled to damages pursuant to §§ 642, 643, 645 II, 280 et seq. of the Construction Contract Act, which are to be calculated analogously to § 648 of the Construction Contract Act. The calculation is on file at our law firm. Based on a net construction sum of 170k, ancillary construction services of 27k, construction services of 100k, and a contribution margin/profit of 46k were calculated. Of the ancillary construction services, all items except for the distribution costs and the license fee of 7k and 6k respectively are to be deducted as saved expenses. The calculated construction services are to be deducted entirely as saved expenses. Accordingly, only the calculated contribution margin/profit as well as the two aforementioned cost items amounting to a total of 60k remain as a payment claim. We hereby request that you pay this amount by ... into one of our designated law firm accounts as authorized recipients of payment. Should it not be possible for you to make the payment in one amount or within the deadline, you are of course welcome to contact our law firm within the deadline to arrange partial or installment payments.