Regret does not know what is java and .net. and this training was for your personal benefit or for benefit of works of the company.
You have posted that no certification was done and actual work was not related to training course.
. You could have written to appointing authority then and there that no certification is done although you were told that proper certification shall be provided hence the bond should be cancelled and if the profile fro which you had applied and wanted to work and excel was not provided you could have stated that you do not want to continue for this reason.
Thus you could have pointed pour the breach by employer and declared him unworthy of being employed with.
If this training was not for any qualification and persona gain then you may not be under any obligation to sign a bond for it too.
Probably it implies there is no addition in your educational qualification.
It is reiterated that shall be appropriate to show the job advertisement, job application, interview cal letter, selection letter, offer letter, appointment letter, standing orders applicable to the company (Certified/Model) and extended to your designation, Bond, resignation letter, acceptance of resignation, FNF statement, service certificate, relieving letter, notice issued by company to a competent and experienced labor consultant/service lawyer specializing in such matters and give inputs in person.
The lawyer that has gone thru each statement and language in each document can advise you the best and fitting reply to the letter issued by the company demanding payment of training reimbursement may put the matter on ‘Shut Up’ Mode.
This usually happens.
IN you do not reply since you have signed the Bond by your Free will hence company can quote from it and may proceed to issue legal notice or approach court.
If you reply still company may decided to agitate in court.
Court looks into reasonableness of the matter and reasonable amounts.
Service Certificate has to be issued to each employee. It is your right.
IT companies in Mumbai are covered by Bombay Shops and Commercial Establishments Act which is so employee friendly and standing orders shall apply if 50 or more employees are employed.
Model Standing Orders:
16. Certificate on termination of service.--Every permanent workman shall be entitled to a service certificate at the time of his dismissal, discharge or retirement from service.
NOTE. - There is a provision under this Act for issuing a service certificate at the time of dismissal, discharge or retirement and every person is entitled to take such certificate.
Consult labor consultant/service lawyer in person with copies of all of your docs.Let your lawyer opinion be final.