This is not only wrong but likely illegal, its clear frrom the case itself that the mother did not commit the infringement and thus she has not got to pay a cent, the law is clear , only those who commit the act are liable not those who pay for the line, she made it clear to others that the line was not to be mis -used and it was also clear that her limited understanding of file sharing meant she didnt actively take part in aiding or colluding with her children to commit infringement.
Its pretty clear whats happened here, this lady has no money for a decent lawyer and has been defrauded of cash by these "ambulance chasing" infringement lawyers who if challenged by a real lawyer would quickly be sent packing.
I,m pretty sure this lady didnt challenge their so called "evidence" nor question how this company obtained her details and bypassed her rights under european data protection laws that state they have to inform her of data gathering that is then linked to her personally, the justice organisations it seems are full of criminals and not just the ones who face the judge.