The correct spelling for the phrase "was customer" is /wəz ˈkʌstəmər/. The word "was" is spelled with a "w" followed by the short vowel "ʌ" and the "z" sound. "Customer" is spelled with a "c" followed by a short "ʌ" vowel, the "s" sound, a "t" and a long "ər" vowel. It is important to spell words accurately to ensure effective communication and to avoid confusion.