Renewal visa 3 months multiple or single entry?

Hi to all! Its my first time here in Expat.com.
Just want to know Where will I renew my visa for 3 months for multiple? Please anyone can suggest me where is the cheapest travel agency? I need the fastest and How much? I am a.bit new here in hanoi..Thanks much for all your answers. :)

Single entry means the Visa is good for entry ONLY.

Multiple means you can leave and re-enter VietNam as often as you like during the Visa validity.

Thanks for your responsed jaitch..But i wanna know how much it cost? Do you know some travel agency ans tours who can help for renew of my visa?..

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