You may find persuading TfL that you needed to get a bus back something of a challenge unless there are special circumstances.
Whilst it may have been annoying and / or inconvenient to have to walk back, the distance between most bus stops in London is 300 - 400 metres according to london.gov.uk
Questions to the Mayor: What is the average bus journey length (and the range " shortest to longest journey length) and what is the average number of bus stops per route? .
www.london.gov.uk
Likewise where is the proof that the stop which was closed was the stop you intended to get off at?
When a stop is closed for example for roadworks, an alternative temporary stop is often provided.