Been offered a good visa deal but would like some advice (wary of fake stamps)

For context:

They mentioned they don't have a website but their name is NP thai visa services or western university

They are based in Buriram and are doing around 50K-70KTHB for a 1 year stamp

So im curious, IF it is a fake stamp, what are the consequences?

Recently I did an ED visa and was promised online classes, then weeks later it was changed to 2-4 in person classes/week, but I cannot do that as I’m busy with my online business

Would love to hear your advice, thank you.

Are there any drawbacks of living on a Non O Volunteer visa?