Cal here from Shopify, thanks for reaching out to us. The $29 charge sounds like the monthly subscription to the Shopify Basic plan, however, the "silver plan" mentioned doesn't sound like any of our offerings.
You can check everything you've been invoiced for on your store by going to Settings > Billing and viewing the breakdown of the invoice.
Likely, it is billing from some third party application that you have installed on your store.
If you're looking for a quick glance at what is contained in your invoice you can go to Settings > Billing, and have a look at the recent invoice you mentioned. It'll give you a breakdown of every charge that it contains.
Hi @Ivyso! I'm sorry to hear that you're having trouble accessing our live support. I've recorded a little video here on the fastest way to get through to our live chat agents who can assist with your account billing query.
Let me know if you're still having difficulty contacting our support agents.