Techavera Solutions - Substandard coaching classes refusing refund

I reached out to Techavera as a working professional looking for GATE coaching in Statistics (ST) on weekends; Techavera advertises themselves as providing coaching for all kinds of competitive exams as well as professional courses.
*. I was told before making payment worth Rs. **,*** that I would get a refund if I don't like the teaching faculty. However, I was given a 'non-refundable' receipt thereafter. Wary of this inconsistency, I got them to explicitly mention a refund clause on the receipt.
*. I was utterly disappointed in my class with the appointed teacher as he turned out to be a mechanical engineer who had no idea about statistics. When he confessed to not knowing much of the ST portion we discontinued the class. Right after that I asked for a refund, but the Techavera people begged me to give them another chance; so I let them arrange for another teacher for next weekend based on the clause that I should get a refund if I am not satisfied.
*. The next teacher was MSc Statistics who did not know English and had no idea about GATE questions. A couple of similar teachers followed and I was left guiding the institute on how to screen the teachers before sending them to teach!
*. I told them finally that I would like to discontinue because this is not working out for me. Upon their constant insistence for more and more chances I told them that I would not be appearing for GATE anymore because it seems like a very impractical option given my extremely busy job life and the kind of help (quality of teachers) available. Now they completely changed their stance and refused to initiate the refund saying that it's non-refundable as mentioned on the receipt; they gave me one of two choices - to keep trying out different teachers until a good one is found, or to take up online lectures if I'm not willing to travel for classes.

I am left feeling appalled at the state of such coaching centers, not only taking the students' time for granted but in fact looting money under false promises. They also had a couple of women talk to me who spoke disrespectfully and ridiculed my reasons for discontinuing while clearly stating that I should have thought about these things before giving them my money! I also offered them to keep *% of the fee for their efforts over these ** days and give me back the rest, but they refused.

Overall, I want to discontinue their services and get reimbursed for the fees I have paid them along with the wasted time and mental trauma of arguing my case for hours on end with their representatives. It must be noted that only * lectures have taken place till date and nearly none of the exam portion has been covered; there should be no problem in making the reimbursement as it is no loss to their business which works on the aggregator model as explained by their staff.