TDS on Purchase of flat from NRI

Dear Sirs / Madams, A flat purchased in December 2017—in Kolkata by my father aged about 80. He is retired and bought the flat from his savings. Sellers – the co-owners ‘Husband and wife ‘..who happen to live/work in Kuwait. Flat purchased value – 23 lakhs , full payment made in cheque, and registration done in December’17. During the negotiation and Registration we only knew that TDS has to be paid on any property worth above Rs.50 lakhs, which did not apply to us as the property is worth only Rs.23 lakhs. Recently after these 8 months, we came across an article in the newspapers about TDS applying to NRI. During the negotiations, agreements, transactions, and Registration , this topic about TDS for NRI never crossed our mind and neither did our lawyer who was involved in registration and neither did the seller bring up this point about the NRI rule for TDS. We are worried to read this article and we need your guidance and help what to do to make sure we do not face any problem in future. if there is any way to get this tax waived or make the seller pay this amount as we are not in a position to pay amount as tax /TDS. Kindly help and guide what is the best way to deal with this situation . Best regards Singha