Is this bond legal?

I was working with a company. In the joining letter it was mentioned that, after the completion of the probation period (3 Months), I can leave the company by serving 1 month of the notice period. But the company ask me to sign 1 year of training agreement and if I fail to do so, I am liable to pay Rs. 50,000 to the company just by clicking 'I Agree' (Not on bond paper or stamp paper just on the company site). I work for the company for 11 months and then due to higher studies, after discussing with the manager I left the company. During my employment, I didn't receive any special training. I was simply guided for 3-4 days on how to do the work. After resigning the company didn't pay me my last month's salary and Now the company is asking me to pay Rs 15,000 (Rs 50,000 bond amount - Rs 35,000 for last month's unpaid salary) amount. 1. There was no mention of a bond on the offer/joining letter. I (had to) accepted the training letter by simply clicking on 'I agree' on the computer. This training agreement wasn't on bond paper or stamp paper. Does it count as a legal training agreement? 2. Since I didn't receive any special training and I work 11 months out of 12 months, do I have to pay the entire Rs. 50,000 amount?