Lufthansa — Regarding the recent booking made

I have recently booked a flight from Mumbai to Milan (booking cide: KLEP6T) from lufthansa website for the month of September. When I booked my flight I did not come across any concession that the company provides to students who travel from India to Europe. Just after booking I came across their page where I could see the student discount. As a first time flyer one will never be aware of such discount been given. When I mailed them and asked if I can still avail the discount, I was refused since I have already booked my tickets.
I just request the company to give me the baggage allowance as per the rules. The documents that they will be requiring as an identity proof as student will be provided.