According to the owner of the business, 27-year-old Michaela Liu, Scarlett also ignored her repeated messages for the £150 item's return.
Michaela is now claiming that Scarlett sent her a series of messages late at night, then blocked her account on Instagram.
Speaking to MailOnline, Michaela said: "I didn't want to read the messages because it was close to midnight and I wanted to be in the right frame of mind to reply.
The messages were gone... and that's when I realised she'd blocked me.
"And then, when I looked on Tuesday morning, the messages were gone, so I messaged her asking why they were no longer visible. And that's when I realised she'd blocked me."
Scarlett's Twitter account has also been deactivated amid the row, although the exact reason for its disappearance is not yet known.
ED! has contacted Scarlett's reps for comment.
The row reportedly started after Scarlett approached MySuitcase about a potential collaboration.
Michaela said she "couldn't believe it" when she heard from the Gogglebox star and claims the two of them spoke via direct message on Instagram, with Scarlett describing that she wanted the boutique's "signature TULLE skirt with crystal stars in black" to wear at New York Pride in return for "lots of posts" on Instagram.
The business owner then alleges that she made the skirt and delivered it for free, but the garment went unacknowledged as Scarlett opted to wear a rainbow-coloured dress to the Pride event.
She told MailOnline that she was left "heartbroken... gutted... deflated", as well as feeling "sick and cheated" by the ordeal.
Writing for her Instagram followers after the story broke, she thanked everyone who had offered support and said: "I feel massively reassured that I've done the right thing. I wasn't sure at first, but... I realise I have done the right thing."
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