A contractor filed a lien in SD on my commercial property which is also my home. He filled a lien on my property having the notary show a date as of Oct 29, 2020 and I received the reg. mail Nov. 7, 2020. The contractor never finished the work and I have hired a home inspector who has documented in writing endless things not finished, incorrect done with questionable workmanship. He has also received excess of 50K in payments and I have not heard from him for months. I keep thinking he was coming back because 6 or 8 months ago he left some of his equipment at my residence. The only thing that he has done recently was sent you young fellows to paint the concreate base that took 21/2 hours and charged me more then $750. dollars and billed me which was dated more then 120 days.
I'm sorry to hear about the trouble you have been having. To tackle the first part of your question as to whether it is required to send a preliminary notice in South Dakota, it depends. On private projects, general contractors are not required to send a preliminary notice. However, if the GC filed a notice of commencement, subcontractors and suppliers must send a preliminary notice on private projects.
If you are dealing with a GC in this case and they weren't required to file a preliminary notice before filing a mechanics lien, this Levelset post in regards to disputing an invalid lien claim will likely be helpful to you.
Good luck!