It is shit to have to do but if you have tried all the options mentioned and the fact we know the forums are monitored in their own words then yes the route of Martin Lewis etc may be your only option.
Personally, I think financial responses like bank details and lost payments should be answered in 24hrs max even non-plus but over a week is much more than their claim of 3-5 days or less.
Before going down that route I have a cunning trick and a good option is to flag your own post Then click the option “Something else” and write the details in there. This will go straight to a FT moderator so you will know they have 100% read about it and you get a reply with a green number in top right corner rather than a pink one.
If that doesn’t work then they really are leaving you little options unfortunately but I would give that a try first