No collection agency shall use any conduct, the natural consequence of which is to oppress, harass, or abuse any person in connection with the attempt to collect any debt. Such conduct includes, but is not limited to, the following:
(1) Using profane or obscene language, or language that would ordinarily abuse the typical hearer or reader;
(2) Placing collect telephone calls or sending collect telegrams unless the caller fully identifies himself and the company he represents;
(3) Causing a telephone to ring or engaging any person in telephone conversation with such frequency as to be unreasonable or to constitute a harassment to the person under the circumstances or at times known to be times other than normal waking hours of the person;
(4) Placing telephone calls or attempting to communicate with any person, contrary to his instructions, at his place of employment, unless the collection agency does not have a telephone number where the consumer can be reached during the consumer's nonworking hours. (1979, c. 835.)