BERLIN/HELSINKI (Reuters) – German Chancellor Angela Merkel ruled out a debt writedown for Greece on Saturday, and a European Central Bank policymaker threatened to cut off funding to Greek banks if Athens does not agree to renew its bailout package. The euro zone’s paymaster and the ECB are both taking a tough line with Greece’s new leftist government, whose leader swept to victory last Sunday promising that five years of austerity, “humiliation and suffering” were over.