The tweet got a lot of support, with many calling Alabanza a trailblazer for speaking up.
Alabanza also explained the safety of queer and transgender shoppers is at risk if attitudes about gender don’t change.
One tweeter responded by @-ing Topshop with a screenshot of a letter they claimed to receive regarding the policy change.
The tweet read: “Um Topshop this was brought to your attention a while back and I was assured you were changing your changing room policy ”
A Topshop spokesperson told HuffPost UK: “All Topshop and Topman customers are free to use any of the fitting rooms located within our stores. The policy was already in place prior to this incident.”
It is not clear what steps Topshop has taken to ensure all staff is aware of this policy change.
But surely the matter would be less of an issue if the policy was signposted in stores?
Topshop’s spokesperson declined to comment on these issues when asked.
This isn’t the first time a high street store has been called out for discriminating against people who are transgender or gender non-binary.
In September 2016, Nicholas Gorham, an actor from New York, US, said they were turned away from a dressing room in Urban Outfitters while attempting to try on womenswear clothes.
Urban Outfitters told HuffPost UK that - like Topshop - there was already a policy in place allowing customers to use whatever changing room they felt comfortable with.
They issued an apology and said they would look into why policies were not followed consistently.
Urban Outfitters has since made this policy change clear with in-store signs that state changing rooms are “open to all persons, regardless of gender identity or expression.”