The agent I used was also Migration Global Assistance. I am sorry to hear about your unfortunate experience with them. I, however, have been very much satisfied with their service and have in fact, referred a few friends already. One of which, after less than 3 months processing his PR visa 189, has already received his invitation and is well on his way to getting that Visa approved.
I think, sometimes, the competence of the agent assigned to you plays a big factor. Migration Global Assistance needs to look into this as even though some of us can vouch for their credibility and good service, there are some who go through the flipside.
What I can say is though, I don't think Migration Global Assistance is a scam. They are a legitimate migration assistance company.
55 points is not sufficient to submit a visa application. It is a wonder why your agent even recommended you pursue your application. Maybe you can file a complaint with the management of Migration Global Assistance.