Is This Sentence Correct?

Is This Sentence Correct?
 

People were selling candy to raise money for a school/church.

I wanted to say:

I'm not sure if you are the person I should address this matter to, but I have a problem with my order.

and I said:

No estoy seguro de si usted es la persona a la que debo dirigirme este asunto, pero tengo un problema con mi pedido.

Did I say it correctly? If not, how should it have been said?

I'm sure it was understood, but I would frame it as a direct question.

«¿Es usted la persona con la que debo ponerme en contacto para resolver un problema que tengo con mi pedido?»

Even simpler:
«Tengo un problema con mi pedido. ¿Con quién debo ponerme en contacto (para resolverlo)?»

A tad more simple:
«Tengo un problema con mi pedido. ¿A quién me dirijo?»

A ver qué opinan los demás. ;)

No estoy seguro de si usted es la persona a la que debo dirigirme (por/acerca de/con respecto a/en lo que respecta a) este asunto, pero tengo un problema con mi pedido.

Kudos for piling up clauses exactly as educated native speakers do, though you slipped a little bit.

But from a practical viewpoint, if all is set in the States, I'm in favour of a more direct, English like approach, as Rusty proposes.

I don't think a correct sentence like the one above is going to be understood by its linguistics merits in 99% of cases, north of Río Bravo, where the standard is grammatically worn out Microsoft Mexican Spanish with touches of Puertorican and institutions and people of good will trying to make it better. It's a new variety of Spanish, and you know, adonde fueres haz lo que vieres (o mejor, di lo que oyeres)

Thank you, Rusy and aleCcowaN. Your input is what I needed.

Now that I have had time to think about this a little more, I have a couple more questions about saying my original sentence:

No estoy seguro de si usted es la persona a la que debo dirigirme acerca de este asunto, pero tengo un problema con mi pedido.

Could I have used "a quien" instead of "a la que"?

Could I have used "debería" instead of "debo"?

Thanks in advance for any input.