There is not enough information here to answer your question. There are just too many variables. A DWI can range from as low as a Class B misdemeanor to a Felony depending on the circumstances of the arrest, your fiance's past, and the facts of the case. However, you should understand how a lawyer could help your fiance. A lawyer could get a court date set and argue for a lower bond. He could then argue that your fiance should receive less time in jail and be put back on probation. A good lawyer should be able to limit the time your fiance spends in jail. Good luck.
The above answer is provided for informative and discussion purposes only. It is not an attempt to solicit business or offer legal advice. No attorney-client relationship is being formed by answering the above question.
Assuming that your fiance is indigent (generally - does not own any property and cannot hire his own attorney), then he can send a letter to the court asking that a lawyer be appointed and requesting that his case be set for a hearing. Under the law, the court is supposed to schedule a hearing within 20 days of a written request, but subject to the court's docket.
This may or may not be a good idea. If your fiance is a first offender for DWI, then the most he is looking at on a probation revocation is 6 months in jail. If he is a subsequent offender, then it could be more time.
If he truly believes that he will sit in jail as he was told by the jailers, then I would request a hearing knowing (as a first offender on a Class B misdemeanor) that the maximum time in jail is 6 months. (Note - he will also lose his driver's license.)
Most lawyers would not charge for a short telephone consultation. You should call a local lawyer and ask for advise on what to do. (Generally lesser experienced lawyers are more willing to help, and will quote a significantly lower fee that you may be able to afford.)