That doesn't make sense. Airlines are not allowed to increase the price. I don't think the rule is that they only need to fix it if the buyer notices and complains. The DOT should very much track these as non-compliance with the rules. In this case it doesn't give the OP the ticket they purchased, but does hopefully help the rest of us in the long term.

Calling web support may be a way to get it fixed if you know that web support exists (or maybe not if we take the example of Op's partner who did call). But the world outside FT doesn't know.