2.12 When contacting water companies by telephone, customers tend to call telephone numbers which are widely advertised on publications, bills, and websites.
2.12 Wrth gysylltu â chwmnïau dŵr dros y ffôn, mae cwsmeriaid yn tueddu i ffonio rhifau ffôn sy'n cael eu hysbysebu'n eang ar gyhoeddiadau, biliau, a gwefannau.