Today received a letter with a collection order fr...

Today received a letter with a collection order from yesterday. I don't know anything about it, don't even do business with the company. telnr or something is not to be found that I have to look up via internet. If I get them on the line, they refer me to the company. This was a sort of pre-collection. Strange working method all the more because it is not mentioned anywhere. and also because it concerns an invoice from yesterday.