Write letter to the AO drawing their attention to the mistake in AY for TDS payment. They should write back asking you to write to the respective bank where payment was made. Then write to the bank attaching the letter of the IT. The bank, in turn, will upload the file in NSDL for change of AY. It happened with me, too.
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This is to inform you that TDS has been paid for AY 2011-12 via XXX Bank on 00/00/2011 which was wrongly paid into assessment Year 2010-11 instead of Assessment Year 2011-12. The copy of the challan is attached for your perusal. Kindly rectify the error by crediting the TDS paid in the Assessment Year 2011-12 (FY 2010-11) and let me have the confirmation of the same.
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