I dealt with a dispute and chargeback through Starling recently. Did it through the app, all done and dusted within a week, money back in my account, very clear communication the whole time.
I had a similar result in a dispute with Dell last year: I'd bought two screens, one in error (didn't think the first transaction went through), which I requested to return immediately, the second I rejected due to several dead pixels.
The second screen was replaced with another, but they didn't issue a return label for the faulty one.
The first screen was returned, but they wouldn't issue a refund (Dell Support kept conflating the two orders, thinking the new replacement meant I didn't need a refund).
Absolute mess of a situation - from Dell's point of view, I'd had three screens but only paid for two and their system somehow didn't process that I'd returned one and was still waiting for another return label for the faulty screen.
I eventually got Starling involved to start a Chargeback: I carefully laid out the situation in great detail, with order & serial numbers, dates, return reference numbers, and quoting Dell's (awful) communication (was helpful to type this up in Word separately, before copy & pasting into the Starling chat section).
Starling Customer Support Agent understood the issue thanks to the detailed message and tried to liaise with Dell to return the faulty screen and confirm they'd received the original, but they experienced the same issue I did with Dell's Support team - conflating orders and stubbornly refusing to acknowledge they still hadn't issued a return label for the second order, nor processed the return of the first...
Starling eventually issued the Chargeback, three weeks before I finally got a response from Dell, confirming they'd received the original screen and had issued a refund for both orders. They also gave me a return label for the screen with dead pixels, which I used to send it back.
Despite trying again to get their Customer Service agents to understand they'd messed up *again* I ended up with a screen plus refunds for all three AND the Chargeback.
I spoke to Starling in complete frustration at the situation, who could only advise I wait and see if Dell disputed the Chargeback - but they ignored it completely.
I've put the money to one side (literally in a pot called "Dell's **** Up"), in case they eventually realise their error and ask for it back, but Starling have confirmed in writing that I (and Starling themselves) have communicated clearly Dell's complete failure to understand a relatively straightforward situation and that there's nothing more we can do.
I only wish I'd bought the Alienware OLED - had I known this would happen!