Do I start Financial Ombudsman Process or go back to Financial Institution.

Sandtree

Undervalued said:

It will cost them a fee of around £500 if you do go to the FOS, whether they win or lose. That may (or may not!) encourage a settlement even if they don't agree with your claim.

Sort of, companies have an annual levy charged irrespective of number of complaints however this gives them a volume of "free" complaints. If they exceed that number then the c£500/case kicks in.