Go Tango - Arbitrary pricing and poor service

I opted for phone repair service from https://gotango.in. First, they quoted a price of **** INR for screen replacement, when I seemed hesitant they offered me a "discounted" service at ****. After keeping my phone for a week, they informed me that there was another damaged part and I would have to pay an additional ****. At this point, I had no choice but to pay them whatever they wanted because they have "partially" serviced but the unusable phone with them. At no point during the preceding week was I informed of the additional charges. I feel like I've been arm-twisted by this company into paying the higher amount.