itself does not contemplate valuation at the time of attachment. It is then argued that the contention regarding hurried auction cannot be raised in the proceedings under Section 144 CPC for which there are various provisions in Order 6 (1994) 2 SCC 3689 XXI CPC which can be invoked in the course of the execution proceedings. The appellant having not invoked any such provisions, the same cannot be raised in proceeding under Section 144 CPC. It is also submitted that Order XXI is a self- contained code and Principal of Estoppel would apply because the appellant, having accepted the conclusion of auction proceedings and choosing not to challenge the same, is now estopped from questioning the validity of the auction. 7. Learned counsel would further submit that the judgments referred by the appellant in the matter of South Eastern Coal Field (supra) has no application in the facts of the present case. It is further put forth that difference in the value of the property in the year 1985