Quality of Painting of the Apartment building

Respected Sirs, Ww gave got possession of our flats in 2022 October/November. We are 40 flat owners in total. Wd are not happy with the painting quality especially carried out in the internal area if our entire flats including the common area. Verbally we have communicated the builder but they dont much seriously taken the matter. (Please be noted that some if the owners have done their own internal painting with their own interest with interior works) I have been worked in the quality Assurance and quality control department in abroad especially in the construction field - and there, such paiting issues will be addressed through the PAINT MANUFACTURER by us. I mean their tech team will inspect, verify and provide a report on the issue. That report is enough for the customer/client to show to the contractor to resolve the matters since all these entire system is working through a very stringent Written and Aooroved specification that any contractor can never deviate from it. Whether we can go through the same way here with the tech support of manufacturer in our case explained above? Or we need to complaint against the builder? Some of the flat owners telling that fir painting we cant do any complaint or take legal actions. What I understand from the paint manufacturers representative itself is that the quality if application of paiting is not to the standard (but off the record only, otherwise he will lose his job, you understand). Whether we will get positive or favourable support from any concerned authority in India? If so how? Please provide your guidence to us to proceed on this matter and to get successful solution. Thanking you Regards krishnan vg from Kerala