Sometimes people regret their decision in hiring a particular lawyer. Sometimes the fault is with the lawyer - some lawyers do a bad job when it comes to returning phone calls, or keeping a client informed about the progress of a case. Some lawyers make promises to their clients and don't follow through. Sometimes a lawyer will mislead a client, causing a break-down of trust. Sometimes there will be a misunderstanding that, although not really the fault of either the lawyer or client, makes it hard for them to work together. Sometimes the attorney-client relationship breaks down for other reasons, such as a conflict of personalities. And sometimes it is the lawyer who will initiate the termination of the attorney-client relationship.
Clients sometimes don't understand that their decision to hire a particular lawyer is not irrevocable. That is, they have the right to change lawyers. They are not stuck working with a lawyer they don't like or believe to be incompetent - while the former firm will typically be entitled to reasonable compensation for work performed to the time a new firm takes over, a client can move a personal injury case to a different law firm.
Changing lawyers during the progress of a case can carry a cost, most commonly in relation to the time it takes to resolve a case, and in relation to how the former law firm is to be compensated for the work it has performed. Sometimes when a new attorney takes responsibility for a personal injury file, that attorney will want to perform additional discovery (to obtain information from the defendant and the defendant's witnesses), or will require the adjournment of imminent court proceedings in order to become sufficiently familiar with the file to provide sound representation at those hearings. If the attorneys are working on an hourly basis, the legal fees will almost always increase due to the additional work required.
At the same time, if your lawyer is mismanaging your case, or is deceiving you about its progress, the risks of staying with that lawyer will usually exceed the costs of remaining with the unsatisfactory lawyer. If your case is being handled on a contingent fee basis, where the lawyers will be paid a percentage of the ultimate settlement or verdict, you typically won't increase your attorney fee by switching firms - the contingent fee would typically be split between the two firms, without increasing the total attorney fee to be paid.
If you do decide to take your personal injury case to a different law firm, make sure you get a clear explanation from any new attorney you consult, in relation to how any fee issues in your case will be resolved between your new lawyer and your former lawyer.
Many clients are angry with their former lawyer, and don't want them to receive even a cent for the services they provided. However, under most circumstances the former firm will be entitled to recover the costs they have invested in the case (such as filing fees, deposition costs, and expert witness fees), and will also be entitled to recover the reasonable value of the work they performed. Often the measure for this value is called "quantum meruit", a fancy term for the amount of compensation a judge decides that they deserve for the work performed. Sometimes the retainer agreement will dictate how fees will be calculated in the event that a client changes firms.
No matter how unhappy you are, in most contingent fee situations a payment to your former firm will not increase the total attorney fee you pay. If that is the case, rather than fretting about how much your former lawyer will get, let your new lawyer worry about that and save your attention for more important things.
Sometimes there will be a dispute between the law firms involved in a case over the division of attorney fees. Sometimes it is necessary for the firms to litigate the issue of their fees before a court, in order to resolve that dispute.
When the attorneys are working on a contingent fee basis, it is usually possible for the plaintiff in a personal injury case to obtain the plaintiff's share of the verdict or settlement, even before the dispute between the lawyers has been resolved. Responsible law firms will seek to have the amounts not in dispute released to the plaintiff, with only those sums which are actually in dispute withheld pending the resolution of the fee dispute.