Revision of return

You have to rectification u/s 154 for this mistake.

Is there any refund claim? If not, then there is no necessity as such to change the bank a/c no.in ITR filed.

But if there is refund claim, then it is to be considered that whether ITR filed u/s 139(1) or 139(4) ?

If ITR filed u/s 139(4), then no provision for Revised Return u/s 139(5)

If ITR filed u/s 139(1), then ITR filed can be revised u/s 139(5) before completion of assessment.

Moreover, in case of 139(4) and also in case where assessee is not ready to file revised return though original return filed u/s 139(1), in both cases, you may wait for ITD Assessment Order and after getting ITD Assessment Order you can rectify the mistake u/s 154 

if there is a refund claim then only you need 2 mention bank a/c no

its fine that you dont want top revise your return

but if you will do the same than it will be ebneficial foer you only because if you will not change it than your refund will be credited in a wrong A/c by Uncome Tax Deptt.

which may cause trouble you and your client only..................

because than you have to send rec. After reciving of refund Cheque so i will advise you its better for you to revise your return in case of refund otherwise leave it  like this only.,.........................