Heat oil in a large non-stick saucepan over medium-high heat. Add scallops. Cook until almost cooked through, about 4 minutes. Transfer to a plate.
Add garlic to pan. Cook 15 seconds. Add wine, chilli flakes and clams. Cover. Reduce heat to medium. Cook until clams have all opened, about 8 minutes. Transfer clams with slotted spoon to bowl. Discard any that have not opened.
Add tomatoes with their liquid to the pan. Simmer until reduced and thickened, about 15 minutes. Stir in the roasted capsicum, clams, scallops and parsley.
Cook angel hair pasta in a large saucepan of lightly salted boiling water until al dente, following packet instructions. Drain well. Add to sauce in pan. Serve at once.