Rangers' main shirt sponsor 32Red have been fined over social responsibility and anti-money laundering failures.
The Gambling Commission says 32Red and Platinum Gaming – both part of Kindred Group – have been fined £7.1 million for the matters.
32 Red Limited, which runs 32red.com, will pay £4,195,655 and Platinum Gaming Limited, which runs unibet.co.uk, will pay £2,937,599.
Both companies have been given an official warning following the investigation by the Gambling Commission.
Rangers' sponsor 32Red's social responsibility failures included failing to identify customers at risk of harm based on their session times, and not having effective enough controls to identify and protect potential problem gamblers.
In examples found by the commission, one customer was allowed to deposit £43,000 and lose £36,000 within seven days.
Some self-excluded or blocked customers were able to register on Platinum Gaming after being blocked or self-excluded on the 32Red platform.
It's also said that Platinum Gaming also failed to identify and interact with customers who may have been experiencing harm.
Gambling Commission Kay Roberts said: “These failures highlight clearly that both operators failed to interact with customers in a way which minimises the risk of them experiencing harms associated with gambling.
“Our investigations also showed that policies and procedures were overlooked, both around customer accounts and anti-money laundering practices.
“Ultimately, it is an example which all gambling operators should take notice of to ensure they protect customers at all times.”
Unibet's logo can be found on the front of Middlesborough's kits.
Henrik Tjärnström, CEO Kindred Group, said: "While we accept the outcome, and the acknowledgment that we have already taken significant steps to strengthen our processes, we also recognise that we need to work even harder to ensure a safe and compliant business.
"We appreciate the Commission's clear recognition that our operations are in an improving position and that we remain fit to hold an operating licence.
"Our commitment to reducing gambling harm across our platforms is a key part of our Journey towards Zero ambition – and we are redoubling our efforts to ensure we continue that progress."
Meanwhile, Rangers are reportedly running the rule over defender Jonathan Panzo.
It's said that the Ibrox club have scouted the centre-back, who is currently on loan with Coventry City from Nottingham Forest.
Michael Beale is aiming to strengthen his squad in various areas this summer.
The England under-21 international moved to the City Ground from Dijon last year.
He was immediately sent to Coventry on loan. He's been an impressive figure at the back for the Championship side.
Panzo is familiar to Beale having worked under him while coming through the academy ranks at Chelsea.
He has since moved abroad for senior spells with French sides Monaco and Dijon before he returned to the Premier League new boys Forest.
