I'm an independent IT provider and I can't tell you how to find me. You have to know someone I currently work for, and be refereed over. The key is someone that fits personality wise with your company. Have you made you issues clear and with the right people? Have you made your frustrations known or is there just a lack of communication?
Let's flip this the other direction, and see it from the IT perspective? What's your monthly IT spend like? Are you paying for services or work and not receiving it? Is there a list of IT projects or tasks that are waiting on money? As an IT provider, my focus is on my customers, but the next thing on my mind is making sure my monthly bills are covered. Bill rates reflect a lot of things, everything from market size, and cost of living, down to if I have a day job and you're second fiddle for that 11am meltdown. Paying for a MSP styled package should give you a static costing for IT, which beats the snot out of an unexpected bill for a $1,000 because a system took a crap.
There are tools out there that an IT vendor or MSP can use to make life easier - things like a RMM package, but those come with a per-pc cost every month. RMM tools can make things like controling Windows 10 updates from happening, or at least not happening before you want. It also helps cut down on trip charges & response times if I can quickly see what you're dealing with and resolve it.
As to finding another IT vendor, chat with other business owners and see who they use. A referral generally is going be be better than opening the yellow pages or Google. Know that when you switch vendors there is going to be a large expense - you're paying the old firm to transition over knowledge and documentation to the new firm, plus the new firm will want to resolve any immediate issues in their eyes. There is many different ways to do the same thing in technology, and determining right and wrong is really a matter of opinion - which we all have.
Do not make business decisions based on a 3 year warranty - it generally only covers the hardware and returning the system back to square one. Make sure you have a solid backup plan, and remember that unless you're an emergency room, no one is going to die.