First, speak with the front desk.  Explain the problem clearly and calmly and ask that it be fixed.

If you have a satisfactory solution to the problem, suggest it.

Allow them adequate time to respond, depending on the nature of the problem.

Stay calm, reasonable and professional.  Don’t make it seem like a personal attack on the person trying to help you. They're human and a sense of reason will bring better results than a fit of anger.

Don’t act like a "big shot" even if you are.  Your claim to be an important frequent guest of that hotel can easily be checked by their computer.  Hotels can track their customers and they may have less than impressive information about you there on the screen. Faking importance usually causes a loss of credibility and will make them less inclined to sympathize with your problem. As a customer you certainly have the right to demand good service.  Just do it in a dignified way.

If you feel that the person with whom you are dealing is not being helpful, ask to speak to a supervisor.

Again, calmly explain the problem and allow them to attempt to fix it.

Once you have tried the chain of command, if you are still unhappy, contact the hotel's customer service department.

Write to them soon as soon as you can after the incident. The information will still be fresh in your memory and you will be within reasonable time limits.

Be as specific as possible.  Describe the problem in detail.  Avoid being emotional or exaggerating.

Always include date, time and location of the incident.

Include your name of course, the reservation or confirmation number and the complete hotel name  Also include any VIP club membership or frequent guest program information, when applicable..

Always retain the originals. Send only copies of any bills, invoices or other relevant paperwork.

Provide the name, title, employee number and physical description of anyone that you dealt with, to the best of your ability.

Describe the actions or lack of, of those people involved.

If you feel that you were treated unfairly, according to company policies or feel the policies are inadequate, question the customer service department.

Clearly state the effect that the incident will have on your future impressions and use of the company. NEVER state unequivocally, that "regardless, I’ll never stay at XXXXXX hotel again". What incentive do they have to rectify your problem ?

If you have of a satisfactory solution to the problem, suggest it.  Give them a chance to win back your confidence, good will and business.

Along with your name, include a full address and a telephone number where you can easily be reached.  If you have a cell phone, include it.  Also your E-mail address might be helpful if your not easily reached by phone.