They had a really good vinegar suce
What's wrong with vinegar? We don't get vinegar sauces over here.
Unfortunately bad fish and chips like a bad curry is bloody horrible. There aren't many good chip shops in Southampton so I go to Harry Ramsden's. It's a chain, but it makes decent fish and chips.
As a general rule if somewhere does fish and chips, donna kebabs, curry and pizza, they don't tend to make any of them well.
There was a brilliant chip shop just down the road from me, it changed owners and they put a donna kebab machine in, and the fish and chips went downhill immediately. I only went there once after they changed owners, once was enough.