You may not have been able to proceed with portfolio rebalancing because your NACH limit was not sufficient. This can happen if there are reinvestment transactions which are of higher amounts than your NACH (or e-mandate) limit.
To get your NACH limit increased, you can drop us an email at email@example.com and inform us of the new NACH limit you would like (in multiples of Rs. 1 Lakh). We will share the NACH form with the new limit, which you will need to print, sign, scan, and send it back to us.
We will then have to cancel your existing auto-debit and apply for the new NACH. Please note, in case you have any investments in progress, then the new NACH can only be applied after the investment (in progress) has been executed.
We also have YouTube videos available for all the common FAQs on SIP and Portfolio Rebalancing. This will hopefully make it simple to understand the entire process and help clarify any doubts that you may have.