These lines are really long. We should keep to 80 lines if we can, as per the styleguide: https://github.com/alphagov/styleguides/blob/master/ruby.md

There's lots of repetition here too. What about a method:
```
def get_cell_content_xml(row, column)
  XmlSimple.xml_in(RestClient.get("#{spreadsheet_end_url}/R#{row}#{column}"))
end
```