I'm sorry to disappoint you but the HA have a choice with regards to controlling the presence of combustible materials and ignition sources in communal areas. It seems to me that they adopted ‘zero tolerance’ policy, i.e. the common parts are effectively ‘sterile’ - free of combustible materials, ignition sources and obstructions based on the fire risk assessment. The alternative would be to adopt the ‘managed use’ policy. There are advantages and disadvantages to both policies. The so called 'managed use' policy would allow residents to store, for example, pot plants and door mats outside their front doors, have framed pictures and notice boards on walls, store bicycles, prams and mobility scooters in places that are out of the way and not likely to cause obstruction. If I were you, I would accept their findings. The HA may quote 'Fire safety in purpose-builtblocks of flats' guide. Although this is only a guidance document (unlike Approved Code of Practices enshrined in law), this guide is widely used by enforcing authorities, amongst others. Good luck!