Paid 1,30,000 for course - they lost my portfolio. Need help

In November-December 2015, I paid for and completed a certificate course from the Mumbai branch of a well-known foreign institution. As a part of the course, I had to make and maintain a portfolio of my work during the course. This portfolio is sent to the UK after the course ends, for assessment purposes, and is returned to the respective local branch of the foreign institution within six months. On 17 June 2016, I received an email from them stating that our portfolios had arrived and we could collect them from the office. I went to their office on 20 June 2016, where after some time of searching, the receptionists told me that they couldn't find the portfolio. I kept in touch with my batchmates and found that others received their portfolios and some received it way back in May. I wasn't informed via email or phone that the portfolios arrived in May. They assured me that they would find it and courier it to me by the 21st so I would receive it by the 22nd. That didn't happen because they lost it. On the 21st they escalated the case to the senior management and on the 22nd they escalated the case to the Delhi head office. I have had many email and phone conversations with them where all they do is say sorry and that they're looking for the portfolio and just can't find it. On the 22nd during a phone call to a representative from the Delhi office, I told her that they had been given enough time, and if they couldn't find my portfolio, they should refund my fees, otherwise I'd have no option but to file a police complaint and sue them. She said nothing in reply to this and Just ignored it. In my emails to them I have also stated many times that either they find my portfolio by Saturday OR refund my fees. They ignore this part, neither agreeing, nor disagreeing. In the latest email the head representative is asking for more time (until 30 June) to find the portfolio. All he's doing is apologising half heartedly. What legal recourse do I have, what can I do? What do I say to them?