Disobedience of court order by thane district tehsil office

Does the court order specifically mention that "Collector" has to attach the property of the Developer ? If Yes, then you can file a contempt petition in the Court which passed the orders for attachment.

As per Section 2(b) of the Contempt of Courts Act, 1971 disobeying a court order tantamounts to 'Civil Contempt'.
Civil contempt means wilful disobedience to any judgment, decree, direction, order, writ or other process of a court.
Complaint of contempt has to be filed within 1 year of the date on which contempt occured.
You can move an application under Section 2(b) of CoC Act, 1971 on your own without engaging a lawyer.

For more details, see this : https://www.mcrhrdi.gov.in/88fc/Week-12/Contempt%20of%20Courts%20in%20India.pdf

Thanks for reply. Yes. The court order directs the 'Jillaadhikari' / Collector to recover money from developer group. I have applied for 'Lokshahi Din' at Tahsildaar and will do so in Collector Office as well in December (they have mandatory period gap of 1 month + 15 day notice). Once I have written replies of 'Lokshahi Din' I will have concrete documents to apply for contemp of court.

Thanks for helping with section details. But I have passed almost 3 years now. Will it still hold contempt?

Since more than one year has passed from the date of order, no contempt proceedings can be initiated against the Collector or any of his/her subordinates.
Your grievances stands at getting the Court order executed. Then, I guess you should file 'Writ of Mandamus' in the Hon'ble High Court praying for orders/directions from the HC for compliance of order by the District Authorities. That is the maximum which you can do as of now.

Good Luck.