Complex sentence: The replenishment oiler SAS "Tafelberg" provided logistical support to the frigates, and picked up the guns in Ambriz after they were towed to Zaire, and took them to Walvis Bay.
Split into simpler sentences: The replenishment oiler SAS "Tafelberg" provided logistical support to the frigates. The guns in Ambriz were towed to Zaire, where they were picked up by the "Tafelberg" and taken to Walvis Bay.