A number of Netflix customers who cancelled their subscriptions have found their accounts reactivated without their knowledge.
Fraudsters have been caught logging in to dormant accounts and resubscribing customers - without their bank details.
Netflix wants to make it easy for customers to rejoin if they later change their minds after leaving the service.
And as part of this, it keeps hold of your data for 10 months after you leave, including your billing details.
This information, it said, is available to members who choose to cancel. They can opt to have it deleted by email.
However, an investigation by BBC Radio 4's You & Yours programme , has found criminals may be exploiting this loophole.
Emily Keen from Oxford cancelled her Netflix service in April 2019, but found her account had been charged £11.99 by Netflix in September.
She said: "I tried to login to my account, but it said my email and password had not been recognised.
Have you been affected by this? Get in touch: emma.munbodh@mirror.co.uk
"It turns out the criminals had changed my login details completely and had signed me up for the most expensive service."
Keen contacted Netflix customer services and was told her card would be blocked and she would be refunded.
However, Netflix went on to take two more payments in October and November, and refunded her only in part.
On twitter, many more customers have complained about similar issues.
"When you cancel your @netflix account yet somehow it gets reactivated the next month?," one user wrote.
Another tweeted: "@netflix someone logged into my Netflix account & reactivated it without my consent & ive been charged. Help."
And non-Netflix customers admit they've been sold the service on eBay.
"If you look on eBay people are selling "life time Netflix subscriptions" for peanuts. I bought one and I was sent, by email some bloke's email address and password to log in Clearly a stolen account. I didn't use it and just deleted the email," one user confessed on social media.
There is a lucrative market for Netflix login details, with criminals selling "lifetime" accounts on eBay for as little as £3.
However, an eBay spokesperson denied the listings - claiming that such items are banned from the platform.
It said all posts would be removed and enforcement action taken against the sellers.
Netflix added that the safety of its members' accounts is top priority, and members who notice any unusual activity on their account should contact them immediately.
A Netflix spokesperson told Mirror Money: “The safety of our members' accounts is a top priority for us, and we are always working to improve this.
"We use a variety of measures to protect our members, notifying users to change their password when suspicious activity is detected, and when there is a sign-in to their account on a new device. If a member notices any unusual activity on their account, they should contact us immediately."
