First of all, it seems that you have issues with the requirements (they are not clear, lack of understanding, lack of commitment,... etc.).

In the case you need to:-

1. Make sure that the team understands the requirements before starting the work.
2. Daily Stand up meeting (10-15 minute) to know three things:- what was done yesterday, what will be dome today and what are the blockers (if any).
3. After every iteration to do a retrospective meeting, to know what went well and what needs improvement.

After that you need to improve the development process gradually.

First of all, it seems that you have issues with the requirements (they are not clear, lack of understanding, lack of commitment,... etc.).

In the case you need to:-

1. Make sure that the team understands the requirements before starting the work.
2. Daily Stand up meeting (10-15 minute) to know three things:- what was done yesterday, what will be done today and what are the blockers (if any).
3. After every iteration do a retrospective meeting, to know what went well and what needs improvement.

After that you need to improve the development process gradually.