I took a look at your account and checked what products are available at your location. The 100 Mbps service that you see on AT&T's website is a speed tier that we don't offer at this time, but you do have the ability to upgrade to 75 Mbps with no change in your current price. The 100 Mbps offering in this case isn't a fiber option but is VDSL similar to what you have now.
You can use our upgrade tool at https://members.sonic.net/connections/serviceupdate/
to request an upgrade to the 75 Mbps service for no increased monthly cost. The change will put you in a new 1 year contract with us but if AT&T fiber or other Sonic products become available to you within that year, there is no early termination fee for upgrading.
The upgrade to 75 Mbps may not require an AT&T technician install but we won't know until we request the change. A provisioning team member will contact you with the appointment date and time (which can be rescheduled) if a visit is necessary, otherwise, you'll receive an email when the speed change completes if no visit is required.