Recovery of due amounts for products supplied to a hotel

Dear Sir,

We are a manufacturer of hotel supply product which locates in Bangkok, Thailand.

We did export to a company in Dubai and allowed them to clear custom already. However, they have not paid to us for a total amount of USD 46,369.16 until now.

They are SME Award company and they are a member of Chamber.

We asked our Thai Consulate to call them. They still refuse to pay.

We would like to hire a collection agency in Dubai, but we worried that if we pay upfront for issuing a legal notice, we still don’t get money.

Please advise if we should sue through the chamber or appoint a collection agency.

If we appoint a collection agency, how can we make sure that we will get money back after paying an upfront fee?