Breaking a Service Agreement.

I was employed by an IT giant in July 2015 and I had signed a service agreement with them which said that if i leave within probation, I'll have to pay them back a big amount, and if my performance is not satisfactory, the company has full authority to throw me out. I completed training in Nov'15 and was posted to one of their offices. I worked there for about a month, but then due to severe medical conditions, I came back home. It was after medical tests that I came to know about a medical condition which is not a severe disease, but is anyhow a medical condition for me and my family. I approached my company and told my HR and Project Manager to give me a transfer to my hometown, or anywhere in North India, since travelling home every 2 weeks for tests and all wasn't possible at all. I had even send them my medical reports. But as per the HR, their team of doctors didn't find the medical reason strong enough for a transfer and they told me to return within 14 days or they will initiate an absconding procedure against me. I requested them multiple times, but all in vain. In the end, after 2.5 months of trying and begging and requesting the HR, I had no option but to resign. But then, from the next week I started getting mails from their settlement department that since I had signed an agreement with them, and I was leaving within the probationary period, I have to pay them an amount of 1.54 lakhs. Already troubled with medical problems, it is not really possible for me and my family to pay such a big amount. I've been getting mails from them since then. Now yesterday, I got a letter from their legal firm as well to pay the amount within a week to avoid severe consequences. Though I have got a job in my hometown 2 months back, and they know the entire case, I am not really concerned about the background verification in this company. And I'll be pursuing higher education next year. So should I actually over burden my family, and arrange for this big amount, or should I ignore these mails from the company?? I am really confused.