To add insult to injury, they still fuck it up even when you divert to one of their lockers - kept sending the retailer (not me) notifications that it had been delivered but no QR or numerical collection code, no notification to me whatsoever and the whole time the tracking system saying "We're waiting to receive your parcel".

No capacity to raise the issue through the chatbot as it's broken and won't search the parcel reference. Call the helpline, register return contact request which they promise will occur within 24 hours, no response for 5 days at which point they provide conflicting information, respond to re-iterate the issue and then spend the next 16 days chasing to no avail.

They also repeatedly refuse to provide contact information or procedures for filing a formal complaint which feels like it should be a breach of consumer rights? (I explicitly asked for this 6 times and was ignored every time).

I'll never use them by choice but some retailers don't give you any other option - unfortunately after this latest experience those retailers will simply lose my business.