Enjoy loans overdue 12 days. What does the text message mean about loans overdue's upgrade?

It is because you didn't pay back the money after some collection that he raised the collection level.

At first, he often called and sent messages to collect money. After a while, he found that the effect was not good, so you stopped spending money.

He will probably call your relatives and friends, or come directly to your place of residence and send you some notification letters. This is the collection of upgrades.