Seemingly,the 'good' relationship between the UK government and the Chinese government has turned sour recently,not that I care about that in the least!
It could be that the cost of a Chinese L visa has shot up dramatically as a result.Some UK citizens believe said visa is still cheap at the new price,but I beg to differ,as the price has approximately trebled!
By the way,it's not a visa extension you applied for,but a visa renewal!