Works every time for me. I am usually going round in circles with customer services or standard complaints teams but never had an issue where this hasn't gotten it resolved. As long as you're polite but clear it gets you out of their hair and helps grease the wheels
The banks and Insurer I have worked for absolutely did have dedicated teams that monitor social media and c-suite "inboxes" and would have greater levels of authority to resolve a complaint before it goes any further.
Glad you got it sorted anyway. Like I said we had 2 months of wrangling with gap insurance cover on a £1500 excess, after getting nowhere reported complaint and was told 8 weeks for response. Couple emails later and phone call from them to say complaint been escalated and paid out and £150 compensation for inconvenience.
Shouldnt have to be that hard but some companies are as difficult as possible - this one has a 1* trustpilot score with every reviewer saying the same thing about delays or claims denied despite loads of evidence provided.