Sendy.co Email Plug-in Troubleshooting

I'm having trouble logging into Sendy.co and need someone with expertise in troubleshooting email plug-ins to help me resolve the issue. My hosting provider has already attempted to fix the problem, but they're unable to identify the cause.

Ideal skills and experience for this job include:
- Experience with Sendy.co and its email plug-in
- Strong troubleshooting skills
- Ability to work with hosting providers
- Excellent communication skills to explain issues and solutions in a clear manner.