So I have had a response from Mr Spin casino on your behalf,
“Although the email advertised a 5 x wagering requirement, the legally bi ding terms on the website clearly stated 50 x.
With this in mind the correct money due to the player would be £86.45 (as paid). As a one off gesture of good will once identity and anti money laundering checks have been carried out we will just on this occasion offer the player a nonnegotiable amount of £400 on top of the money already collected. I hope this can bring the matter to a close “
I personally think this is a fair result as they are no IBAS registered.