I am an NRI and got a loan disbursed through a bank. I had
authorised a POA (my brother) to sign the documents. He signed the
documents whereever the bank-rep had marked with X and also made
sure to clearly select the option FIXED RATE terms and to not select
MONEY MARKET CLAUSE (MMC). After the loan was disbursed - the POA
recd one original set of loan agreement and he noticed in two pages
where he never signed - he finds that a new clause (MMC) was sticked
in the page and on the sticker someone has forged (most likely a
bank employee in the loan department) POA's signature. My POA
suspects it could be a forgery on the following reasons (1) he did
not sign those pages (as was not marked for signature from the bank
(2) it is not his signature (3) ink and pen are different (4) there
is also spelling mistake in the signature.

Question:
Should I (or POA) directly contact the bank regarding this forgery?
Should I (or POA) instead file a civil/criminal case in court?
How would it impact the loan we have been sanctioned?

Any suggestion would be appreciated.