Retraction of statement cannot be made even without any strong supporting evidence and mere mention of ill health not sufficient to disprove the contents of nine month old statement

During the course of income tax raid, I surrendered certain Kishan Vikas Patra with a undertaking that same may be used towards tax liabilities/tax dues.I have filed necessary revised returns for six years in persuant to the income tax raid.

I also requested in the said income tax returns that Kishan Vikas Patras may be encashed and proceeds thereof may be adjusted towards tax dues. The income tax authorities have not done so yet.
Kindly advice me/ inform me about certain case law which allows encashment of said Kishan Vikas Patras etc. for adjustment of tax liability.