Any recommendations for VPN services would be appreciated.
Well, you're wrong. Many people have had success with VPNs. It doesn't work for everyone, but if the ISP is throttling, which many are doing, or if there are routing issues, the VPN can circumvent that issue.
Testing with a VPN is free and it can be done in a matter of minutes. Upgrading a service plan as you suggest takes money and time. I'd choose a VPN test first.