I'm guessing here but it seems this is in India, right? I have worked with a number of Indian developers, e.g. WiPro and Infosys. They are often fairly new developers (< 5 yrs) and very clever. There are some cultural issues that apply here. From what I have seen most of your team will not have had much formal training but will have learnt on the job. This means they have probably done a lot of 'hacking' without paying much attention to testing, and now the project needs refactoring to smooth out the recent features that have been bolted on. However, this is probably too difficult to do because the code base is too disorganised.

I recommend you get in a senior developer with experience of TDD and large systems. Have a fresh start and boost morale by showing how a new approach can help clean up the code. It will need your support to give them the time to add the tests, refactor and clean up the code. Progress will appear to stop for a while, but it is well worth it. You will end up with a much better product.