https://www.fluentu.com/blog/business-english/english-for-customer-service/
https://www.wixanswers.com/post/customer-service-phrases
https://www.lawlessenglish.com/learn-english/grammar/negative-prefixes/
https://elt.oup.com/student/englishfile/advanced3/vocabulary/prefixes/vocabulary09_01?cc=cz&selLanguage=cs