How do you counter a fed Fiora?

According to http://champion.gg/champion/Fiora her build + masteries + Dragon buff will give you about 300 bonus AD and 416 AD total.

According to the Wiki her passive scales like this: 3% (+「 2.7 + (0.1 × Fiora's level)% 」per 100 bonus AD) of target's maximum health. So 3% base +4.5% per 100 bonus AD. In total her passive will be dealing 16.5% max health true damage and an ultimate will be dealing 66% max health true damage. So as a full build Taric I have around 400 armor and 4000 health or something like that. Every passive proc is 660 true damage and an ultimate is 2650 true damage total. Taking her basic attacks with Last Whisper into account, you're dead no matter what you. I was useless because the enemy had a FIora and the game lasted over 20 minutes. Here is the game I'm talking about. Pretty much the ONLY thing a tank can do is hope to build enough damage to kill her first or be with at least 3 other teammates. 1/3 of her damage to champions was true damage, even with 400+ AD. She can kill anyone she chooses instantly then heal for 400 per second from her ultimate for 5 seconds while still hitting vitals, gaining movement speed, healing from vitals, AOE lifesteal damage, etc. The fuck can you do?

All three tanks on both teams had the least amount of gold. Don't go telling me "Fiora is fine", answer the damn question and tell me what I can do as a tank to a Fiora.

Also, she has a 50% banrate and I don't think that's normal.