FRANKFURT (Reuters) - Trade union Verdi called on workers at seven German Amazon warehouses to go on a three-day strike that will coincide with “Black Friday” discount shopping sales on Nov. 27. Scheduled to begin with Wednesday’s night shift, Verdi is demanding better pay and working conditions. Verdi has been organising strikes at Amazon in Germany - the company’s biggest market after the United States - since 2013, most recently last month during its “Prime Day” promotional event. An Amazon spokesman said at the time that the company offered “excellent” salaries, with benefits and working conditions comparable with other important employers. The U.S. retail giant has seen sales soar globally as restrictions to prevent the spread of the coronavirus sent consumers online, making it difficult for some bricks-and-mortar shops to compete. Verdi argues this has strengthened the case for higher wages, adding workers were not sufficiently protected against the spread of the coronavirus. Last week, Amazon bowed to government pressure in France to postpone its local Black Friday event by a week to help local shopkeepers struggling with a nationwide lockdown.