These morons texted you?
Great, save the texts, show the teacher if they need proof.
In the real world you write them up or coach them if they've already been talked to. OP told them that making up a value wasn't going to cut it, they laughed at him, so he can't exactly fire them. In the real world, say accounting, you make up values, you're either doing Hollywood bookkeeping or getting your ass fired. You unfortunately can't fire your group mates in school.
Great, save the texts, show the teacher if they need proof.
I'm going to present a different situation - you screwed up originally by not dealing with them having a poor performance in the first place. Group work sucks but is a great example and learning experience in real world where you'll have B and C players working along with the A players. The best A players know how to either inspire / motivate/ uplift the B or C players on their team or deal with the dead weight.
In the real world you write them up or coach them if they've already been talked to. OP told them that making up a value wasn't going to cut it, they laughed at him, so he can't exactly fire them. In the real world, say accounting, you make up values, you're either doing Hollywood bookkeeping or getting your ass fired. You unfortunately can't fire your group mates in school.