I'm not sure how VMware PSO works but I know other software vendors typically just pick a certified vendor close by, however this can vary on the consulting company/partner. Some are good, while others are poor.
The fact that you didn't get a SOW is odd. When I was in the consulting gig we always had a SOW or a project plan for every company engagement. This is good for both parties as it establishes a list of requirements the client wants, which is a list of requirements the work/project has to be completed from the consultant side. This is also known as Key Success Factors or Critical Success Factors. It gives both sides a way to measure when the job is completed. It also protects the consultant from getting sucked into extra work as they can fall back on the plan and state it wasn't in. Without a SOW or plan its hard to argue when anything is "complete" or done to expectations.
I'm sorry to hear you have had a bad experience with the PSO, maybe they can voucher you another vendor to come out to correct the poor work the first few did.
Either way I think your on the right track to finding a good vendor that will work with you to successfully implement your requirements. Vendor relationships can do wonders for a company when done correctly :smileyhappy: