Ah, German nitpicking... Willkommen in Deutschland!
But have no fear, since this is Germany there's a well-defined process for appealing. The German Embassy in Manila, Philippines has a useful fact sheet about how to apply for a "remonstration against" (their term!) the visa rejection, and I'm sure more or less the same process applies for the Chennai consulate. Quoting the relevant bits:
You can remonstrate only in writing, and your remonstration must
contain the following details:
- Your name, first name, date of birth, place of birth, and the number of your passport
- The date your application was rejected
- A serviceable address that contains the street name, house- or apartment number, City/ Town/ Village, postal code, if applicable:
please state your e-mail address
- The remonstration must be signed by your own hand (a remonstration by a third party e.g. your sponsor, can only be accepted and
processed if you have given your sponsor a power of attorney, which is
submitted with the remonstration).
If you applied for a visa of the category „C“ (Schengenvisa), the
deadline for filing the remonstration is one (1) month after your
received the letter of rejection.
You can submit by mail, fax or e-mail, but if e-mail, you have to send in a scan of a printed letter with your signature.
And obviously the better you can explain the discrepancy (a revised letter and/or note from your office should do nicely), the higher the chances of success.
Incidentally, if your remonstration also fails you can apparently try once more with the High Court in Berlin, but that's probably a bit overkill for a tourist visa...