It's laid out quiet clearly in the article:

"She was unhappy with her barrister and was told he would not be able to continue representing her after she expressed her dissatisfaction.

However, due to industrial action, no other barrister can accept the case. With no replacement found, Judge Peter Rook QC has told Anderson, 40, that she must represent herself."

They're on strike. They will still represent clients but they will not pick up clients of another barrister, presumably because the original barrister will get no or less pay if that happens.