FOI - Mayor's Campaign for "Britain to Stay in Europe"

With regards to the website page

https://www.london.gov.uk/about-us/mayor-london/mayor-and-his-team/mayor-london-campaigning-britain-stay-europe

where the Mayor of London announces and  is campaign for "Britain to stay in Europe"

and the ad published on Facebook, whose screenshot is attached to this email, I hereby request the following information in accordance with the Freedom of Information Act 2000 (FoI):

a) total budget commitment for the Mayor's Campaign for "Britain to Stay in Europe"

b) shares of budget commitment by media / social media channel (named entities, not entity categories)

c) list of the vendors that have a contract with the Mayor of London for the planning, design, execution and monitoring of the campaign

d) values of the respective contracts

e) actual total expenditure to date (25/05/2016)

f) legal basis of the budget commitment

g) final approver of the budget commitment