Here is where you can complain. Metro used the most offensive sexist stuff on social media.
https://www.ipso.co.uk/complain/
Clause 1 (Accuracy)
i) The Press must take care not to publish inaccurate, misleading or distorted information or images, including headlines not supported by the text.
ii) A significant inaccuracy, misleading statement or distortion must be corrected, promptly and with due prominence, and — where appropriate — an apology published. In cases involving IPSO, due prominence should be as required by the regulator.
iii) A fair opportunity to reply to significant inaccuracies should be given, when reasonably called for.
iv) The Press, while free to editorialise and campaign, must distinguish clearly between comment, conjecture and fact.
Clause 12 (Discrimination)
i) The press must avoid prejudicial or pejorative reference to an individual's race, colour, religion, sex, gender identity, sexual orientation or to any physical or mental illness or disability.
https://www.ipso.co.uk/editors-code-of-practice/