3 Month business visa extension?

You can extend 2 times 

in Da Nang they said 1 time for 1 month. where is it 2 times for 3 months? (HaNoi / HoChiMinh)

also when I asked about extending they needed a work permit, which I won't have as I am not eligible.

I don't know about that. But I believe you can extend 2 times after the first entry.
Many people did in Vietnam. I am in HCMC. You can search and see in this website about similar topics.
https://www.expat.com/forum/219-3-visas-vietnam.html

smellymoo wrote:

in Da Nang they said 1 time for 1 month. where is it 2 times for 3 months? (HaNoi / HoChiMinh)

also when I asked about extending they needed a work permit, which I won't have as I am not eligible.

So is it in HCMC that I can renew 2 times 3 months each time?

The thing is that I will not have anything (no work permit, residency, etc) so when I asked at an official immigration office in Da Nang, they said that I need a work permit to get 1 month extension.

If I go to a travel agent, and get a visa extension even though it is clearly not allowed, will it cause me problems? for example will I get kicked out and black-listed? will anyone notice, etc?