The problem is that Extendnet won't talk to my client.
That is not very professional of them.
I missed renewing a domain a few years ago and the first I knew about it I stopped receiving emails. I contacted the company that look after my domains and they renewed it; from memory as cpradio says there is a grace period. Keep copies of your emails as partial proof in case you need to contact the company that looks after .com names.
A quick Google search returned this from the Tucows website:
Partial list of Grace Periods:
.COM, .NET, .ORG, .INFO, .BIZ, .US, .NAME, .TV and .CC – 40 days
.CA – 30 days
.UK domains resolve for 30 days past their expiration date after which they no longer reside with Tucows. Your Domain Provider can recover the domain for an additional 60 days by placing a transfer request for the domain.
.CN and .DE – have no Grace Period; they are deleted the day after their expiration date
During the Grace Period, all services (such as the website and email) cease working until the name is renewed (if and when this happens). As well, name server/DNS changes are not possible. When the domain expires the DNS is temporarily changed, and a web page explaining the need for renewal may be shown. When the domain is renewed, the DNS will be changed back to the previous DNS entries.
At the end of the Grace Period one of three things may happen:
The domain is marked for deletion, and with most types of domain names this will place the domain name enters a “Redemption Period” (also called “Pending Delete Restorable”), which is an additional period of time provided to recover the domain name. The cost to recover the domain will be more than the cost of a renewal, and recovery is only available to the former domain owner. The precise time when the domain is finally deleted depends on the Registry, but many domains are deleted 30-35 days after entering the Redemption Period.
A third party expresses interest in the expired domain name via an online auctioning system, and when the Grace Period ends, the domain is sold to the highest bidder. Domains that are auctioned off cannot be renewed or “redeemed”.
Tucows acquires the domain name for its private domain portfolio, and upon the Grace Period ending, the domain is not deleted. Should the former domain name owner inquire about obtaining the domain name via their Domain Provider, the domain can be returned to them in a process similar to “redeeming” a domain. Additional recovery and administrative fees may apply.
For information on renewing or redeeming your domain name please contact your Domain Provider directly.
I know Nominet look after .co.uk domains but I do not know who looks after .com ones. It would be worth finding out and contacting them.
Does your client have an account with Extendnet or was she looking at her old control panel?