There are a few way of rephrasing this to avoid the implication that the services stopped. Which you use depends on the verb tense you want to use, although the first example is closest to what you had written.
For the next two months, A hired B's services twice a week.
For the past two months, A has been hiring B's services twice a week.
It's assumed that "the story" will continue after this, indicating if the two-month pattern changes or not.
To address some comments, the use of "A repeatedly hiring B's services" may sound strange, but it's actually quite acceptable in the right context. Although hire can be associated with an employer / employee situation, it certainly need not be.
"I'd like to hire your services this week—and then twice a week afterwards."
Dictionary definitions include both uses of the word. You typically "hire the services" of somebody who performs temporary, time-limited work, such as a babysitter, a gardener, a chiropractor, and so on. Such people are not given a salary but repeatedly "employed" as needed.
Stylistically, such phrasing used to be in much more common use—especially when people were speaking formally. (Before the mid-twentieth century, the upper class were quite often "hiring the services" of working class labourers.) These days, you don't hear it as much. But it's certainly not wrong.