Hi @Rika, this sounds great and thanks for setting out the long-term vision. Lots to keep you busy by the sounds of it!
I was a victim of fraud, via PayPal, last year and found the whole process very frustrating (Advice Needed - Fraud with Monzo) - it required me to doing quite a lot of my own digging, after having a chargeback fail, to collate lots of evidence to re-present this back to Monzo.
The key to my eventually successful claim / defence was receiving the Mastercard transaction data report against which Monzo had made the decision (TL;dr it stated my address as the Delivery Address for the transaction which was factually incorrect).
Once I had identified the PayPal transaction ID from this (not as easy as you would think 
), I was able to chase up details directly with PayPal and the merchant, FootAsylum.
As part of this project, is there something here that needs to be factored in around providing evidence to customers where chargebacks are refused / declined? Whilst I’m sure some of these decisions are correct, others (like me) are no doubt going to have decisions made against them incorrectly and need Monzo’s help / guidance to work through this.
Throughout the process I went through, I constantly felt Monzo was battling against me, being unhelpful, not raising important factors (‘hey customer, have you considered you may have been the victim of identity theft?’), and being too trigger happy with raising a formal complaint on my behalf.
The key things I needed to argue my case were the transaction details, someone pointing out the PayPal transaction ID, someone telling me I was a victim of identity theft, and informing me of what I needed to do if I wanted to argue my case. Instead I got a ‘final decision’ 
.
Anyway, I was eventually successful getting my money back but it was anything but a frictionless process - I look forward to your contributions to the end-to-end process and hope I never have to use them 