While you are justifiably very upset, may I suggest that you be as calm as possible when presenting your situation. If you will speak when you are extremely distraught you may be ineffective. If you feel you won’t represent yourself in a good light, maybe have someone speak to these people on your behalf.
Since you only experienced the problem after this recent washing, you might need to speak to the owner of the salon who washed your wig and hear what she has to say. You may also need to speak to the person who sold you the wig as she would likely be the representative between you and the wig company.
Unfortunately after 3 years you may not have much if any recourse in terms of replacement. Hopefully they will examine the wig carefully and will be able to rectify the problem (even if they charge the cost of the repair)so that you will be able to have continued use from your once beautiful wig.
Good luck!