Sunviet Travel (Visa Expert): Too Good to be True?

Hi everyone!

I'm an expat living in Phu Quoc Island (Southern Islands of Vietnam) for a year now. For the passed months I've been exiting the country to my liking due to visa thingy and also a chance to have my holiday. I heard of VISA extensions but never bothered me since I always prefer exiting.
So, my issue is, I'm thinking of extending my visa next month and I happen to search SUN VIET TRAVEL (VISA EXPERT) online, and as stated on their site they offer  pretty good deals.
So, I tried searching if it's just for advertisements and tried checking travel sites on reviews about it. But there are none.
I'm a little doubtful to use their service but at the same time tempted. It's my passport at stake! o.O

So, does anyone of you heard of this Travel Agency? or happen to use their service.?

Hoping for your opinions! Thank You!
_June_

I can vouch for Sunviet travel and Johnny Le Manh Hung. I visited their office on Tran Hung Dao near PNL, saw 4 busy workers there, and a stack of 25+ passports in process. I have used  Johnny's services twice.  Once for a visa approval letter for airport visa-on-arrival. Then on November 19, I got a 3 month visa extension. I contacted him via email, he sent a nice woman who spoke English to my house to pick up my passport, and 1 week later she returned and I paid $50 on delivery. (An extension is just a stamp with dates in your passport. I assume you are in Saigon with your passport, otherwise would you mail your passport to Sunviet? No travel agents in Phu Quoc? ) He is active on the Facebook group "Vietnam Visa Agents"  where you will find lots of other visa agents. You can search Expat.com for 'extension', I read one guy got a lower price from a travel agent recently.

Hi... wow thanks for the information! Now, I'm in no doubt at all to use their service.
I talked to Johnny via phone and he said it's okay for me to just mail my passport to Ho Chi Minh. Which is a little scary but I guess I have no choice.
Anyways, I'm still thinking about it, either I travel to Saigon for some days to process the visa or exit again or mail him my passport.
Sad but extending, renewing and processing visas here on Phu Quoc is really a fuss. Travel Agency either don't do it or charge you with high prices. My friend who got his visa extended last October caused him 200USD for 3 months. I'd rather buy a ticket to Siem Riep. :)
Anyways, thank you so much for your help! Means a lot! Xin Cam On! :)