Parcel Delivery Service Within Bangkok Available?

Hello, is there a parcel delivery service (a messenger service) available within Bangkok?

I want to send a parcel from a big Sukhumvit hotel to an office building in the outskirts of Bkk. Of course i could use the post office, but want it to arrive fast. I can provide a correct address written in Thai script. The parcel would be about 35x45x10 centimeters @ 1 kg. I am not connected to any business or administration in Thailand.

Can i ask the hotel reception to arrange this? Can i ask a regular passenger taxi driver or a motorcycle taxi driver? Should i close and seal the package just like for the post office or would a more open bag – with the unexpensive items + papers visible – be enough? Do you have a rough estimation of the costs (maybe similar to a regular metered taxi)?

Do you have a phone number of a service i can call? (English reply preferred, even though i speak basic Thai.)

Thanks for all practical tips!